Battle Logic Edits

Author(s): Lmaokai
Implementation & Research: HGSS Decompilation, Platinum Decompilation, HG Engine, DarmaniDan, MrHam88, Yako, Lhea, Chritchy, Fantafaust, Aero, Paille92, Shogo Kawada Fan, Memory5ty7, Lmaokai

This page is a collation of hex edits to the battle logic in Generation IV Pokémon games. This primarily focuses on simpler aspects where only a single byte needs to be edited, such as Iron Fist's damage multiplier. Any hex editing offsets or files present on this page are for known good US versions of the relevant games.

These edits rely upon a basic understanding of hex editing and unpacking NARCs. An initial grounding in these subjects can be found in the following:

• Hex Editing Primer
• Unpacking NARCs

This information comes from tutorials, guides, and research shared via other means previously (within the Kingdom of DS Hacking! Discord server, pastebin, GitHub etc.), with some additional content and context added. Attribution should be given to the researchers and original tutorial writers, these are noted at the beginning of the relevant sections (and collectively at the top of this section).

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Table of Contents

• Statuses

  • Burn Damage
  • Paralysis Speed Reduction
  • Sleep Duration
  • Freeze Thaw Chance

• Abilities

  • Iron Fist Damage Multiplier
  • Pickup Activation Chance
  • Honey Gather Rate
  • Ice Body End-of-Turn HP Restoration
  • Heatproof Burn Damage Reduction
  • Quick Feet Speed Multiplier
  • Slow Start Stat-Reduction Duration
  • Rain Dish End-of-Turn HP Restoration
  • Reckless Damage Multiplier

• Item Held Effects

  • Leftovers End-of-Turn HP Restoration
  • Black Sludge End-of-Turn HP Restoration
  • Black Sludge End-of-Turn Damage for Non-Poison Types

• Move Effects

  • Aqua Ring End-of-Turn HP Restoration
  • Binding Moves End-of-Turn Damage
  • Binding Moves Duration

• Weather

  • Hail End-of-Turn Damage for Non-Ice Types

• Bug Fixes

  • Fire Fang vs Wonder Guard
  • Trainer AI Water Immunity Check vs Dry Skin

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Statuses

Burn Damage

Sources and Credits: DarmaniDan, HG Engine, Plat Decomp, HG Decomp

Unpack the relevant NARC, open the specified file, and change the byte at the provided offset:

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/0/1	1_26.bin	0x30	08
Platinum	/battle/skill/sub_seq.narc	sub_seq_26.bin	0x30	08
Diamond/Pearl	/battle/skill/sub_seq.narc	sub_seq_26.bin	0x30	08

Burn damage in Gen IV is 1/8^th of the Pokémon's max HP. The battle logic calculates Burn damage by dividing the Pokémon's max HP by an explicitly defined value, in this case 8.

As an example, to change Burn damage from 1/8^th of the Pokémon's max HP to 1/16^th (matching Generation VII onwards), change the byte from 08 (8 in decimal) to 10 (16 in decimal). Make sure to pack the NARC after saving the file.

Paralysis Speed Reduction

Sources and Credits: Lmaokai, Plat Decomp (1, 2), HG Decomp (1, 2), Online Assembler and Disassembler

Open the relevant file and go to the provided offsets:

Game	File	Offset (Battler 1)	Vanilla Byte	Offset (Battler 2)	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x185CA	B6	0x18776	A4
Platinum	Overlay 16	0x17FCA	B6	0x18176	A4
Diamond/Pearl	Overlay 11	0x16EC6	B6	0x1702C	A4

You can also search for these bytes instead

	Battler 1	Battler 2
All Games	B6 08	A4 08

Paralysis in Gen IV decreases the Pokémon's Speed by 75%. Unfortunately, this is not achieved by simply dividing the Pokémon's Speed by 4. The battle logic calculates the decreased Speed by performing logical shifts. More specifically, the Pokémon's normal Speed is taken as a binary value, and those bits are shifted to the right by 2 bits, resulting in the same effect as dividing the value by 4.

To illustrate, take a Pokémon with 100 Speed. In binary, that is represented as 0110 0100. Shifting the bits to the right by 1 bit results in 0011 0010, or 50 in decimal. Shifting the bits to the right by 1 bit once again (for a total of 2 shifts) results in 0001 1001, or 25 in decimal.

We can change the number of logical shifts from 2 to 1, effectively changing the reduction from 75% to 50% (matching Gen VII and VIII). To do so, change the following bytes at the two offsets provided above:

Battler 1	Battler 2
B6 --> 76	A4 --> 64

Sleep Duration

Sources and Credits: Yako, Plat Decomp, HG Decomp, HG Engine

Unpack the relevant NARC, open the specified file, and change the byte(s) at the provided offset(s):

Game	NARC to unpack	File	Offset (Maximum Addend)	Vanilla Byte	Offset (Base # of Turns)	Vanilla Byte
HeartGold/SoulSilver	/a/0/0/1	1_18.bin	0x250	03	0x254	02
Platinum	/battle/skill/sub_seq.narc	sub_seq_18.bin	0x250	03	0x254	02
Diamond/Pearl	/battle/skill/sub_seq.narc	sub_seq_18.bin	0x250	03	0x254	02

Sleep in Gen IV lasts 2-5 turns, but effectively prevents movement for 1-4 turns. The battle logic calculates the number of turns through the following process:

1. Generate a random number from zero to an explicitly defined value, in this case 3 (the 'Maximum Addend' or range)
2. Add it to another explicitly defined value, in this case 2 (the base number of turns)

This results in (0 + 2), (1 + 2), (2 + 2), and (3 + 2) as possible outcomes for the number of sleep turns, which effectively prevents movement for 1, 2, 3, or 4 turns.

As an example, to change Sleep to instead last 2-4 turns, effectively preventing movement for 1-3 turns, (matching Gen V onwards), change the byte at 0x250 from 03 (3 in decimal) to 02 (2 in decimal). This results in (0 + 2), (1 + 2), (2 + 2), as possible outcomes, effectively preventing movement for 1, 2, or 3 turns. Make sure to pack the NARC after saving the file.

Freeze Thaw Chance

Sources and Credits: Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x13E12	05
Platinum	Overlay 16	0x137EE	05
Diamond/Pearl	Overlay 11	0x12998	05

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	05 21 A7 F6
Platinum	05 21 93 F6
Diamond/Pearl	05 21 AB F6

A frozen Pokémon has a 20% chance of being thawed out on each of its turns in Gen IV. The battle logic calculates this chance through the following process:

1. Divide a random number by an explicitly defined value, in this case 5
2. Compare the remainder to 0
3. If the remainder is not equal to 0, the Pokémon remains frozen
4. If the remainder is equal to 0, then the Pokémon thaws out

Here is a table of bytes and the resulting thaw chance.

Byte	Resulting Thaw Chance
05	20% (Vanilla)
04	25%
03	33%
02	50%
01	100%

Abilities

Iron Fist Damage Multiplier

Sources and Credits: MrHam88, Yako, Plat Decomp, HG Decomp

Open the relevant file and change the byte(s) at the provided offset(s):

Game	File	Offset (Multiplier)	Vanilla Byte	Offset (Divisor)	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x1FF44	0C	0x1FF48	0A
Platinum	Overlay 16	0x1F94C	0C	0x1F950	0A
Diamond/Pearl	Overlay 11	0x1E520	0C	0x1E524	0A

You can also search for these bytes instead

	Vanilla Bytes
All Games	0C 20 60 43 0A 21

Iron Fist increases the power of effected punching moves by 20%. The battle logic calculates the increased damage by multiplying and dividing the move's power by explicitly defined values, in this case 12 and 10, respectively.

As an example, to change the boost from 20% to 50% (matching similar damage-boosting Abilities in later generations, such as Mega Launcher or Sharpness), change the byte at the multiplier offset from 0C (12 in decimal) to 0F (15 in decimal).

Pickup Activation Chance

Sources and Credits: Lhea, Aero, & DarmaniDan, Lmaokai, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0xC852	0A
Platinum	Overlay 16	0xC62A	0A
Diamond/Pearl	Overlay 11	0xBCB2	0A

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	0A 21 AE F6 40
Platinum	0A 21 9A F6 FE
Diamond/Pearl	0A 21 B2 F6 04

Pickup has a 10% activation chance. The battle logic calculates this chance through the following process:

1. Divide a random number by an explicitly defined value, in this case 10
2. Compare the remainder to 0
3. If the remainder is not equal to 0, then Pickup does not activate
4. If the remainder is equal to 0, then Pickup activates

Here is a table of bytes and the resulting Pickup activation chance.

Byte	Resulting Activation Chance
0A	10% (Vanilla)
09	11%
08	12.5%
07	14%
06	16.7%
05	20%
04	25%
03	33%
02	50%
01	100%

Honey Gather Rate

Sources and Credits: Lmaokai, DarmaniDan, Plat Decomp (1, 2), HG Decomp (1, 2)

Honey Gather has a variable activation chance, starting at 5% if the Pokémon is between levels 1-10, and increasing by 5% every 10 levels, ending at a 50% chance at levels 91-100.

The battle logic calculates this chance through the following process:

1. Get the Pokémon's level
2. Depending on the Pokémon's level, pull a specific value from the Honey Gather Rate Table (see below)
3. Divide a random number by an explicitly defined value, in this case 100
4. Compare the remainder to the value pulled from the Honey Gather Rate Table
5. If the remainder is greater than the value, then Honey Gather does not activate
6. If the remainder is less than the value, then Honey Gather activates

Honey Gather Rate Table

Levels	1-10	11-20	21-30	31-40	41-50	51-60	61-70	71-80	81-90	91-100
Value	5	10	15	20	25	30	35	40	45	50

Here are the offsets for the Honey Gather Rate Table:

Game	File	Offset
HeartGold/SoulSilver	Decompressed Overlay 12	0x35198
Platinum	Overlay 16	0x33974
Diamond/Pearl	Overlay 11	0x30B9C

You will see the following string of bytes that corresponds to the values of the Honey Gather Rate Table:

05 0A 0F 14 19 1E 23 28 2D 32

Given how the logic for Honey Gather works, the values in the table are effectively the literal rates for each level range respectively. As an example, if you wanted Honey Gather to have a 50% rate from levels 1-50, and a 100% rate from levels 51-100, then replace the ten bytes with the following:

32 32 32 32 32 64 64 64 64 64

Ice Body End-of-Turn HP Restoration

Sources and Credits: Lmaokai, DarmaniDan, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0xA3F6	10
Platinum	Overlay 16	0xA1CE	10
Diamond/Pearl	Overlay 11	0x985E	10

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	10 21 11 F0 5E
Platinum	10 21 11 F0 72
Diamond/Pearl	10 21 10 F0 4E

Ice Body restores 1/16^th of the Pokémon's max HP. The battle logic calculates the HP restoration amount by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change the HP restoration from 1/16^th of the Pokémon's max HP to 1/10^th, change the byte from 10 (16 in decimal) to 0A (10 in decimal).

Heatproof Burn Damage Reduction

Sources and Credits: Plat Decomp, HG Decomp

Unpack the relevant NARC, open the specified file, and change the byte at the provided offset:

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/0/1	1_26.bin	0x50	02
Platinum	/battle/skill/sub_seq.narc	sub_seq_26.bin	0x50	02
Diamond/Pearl	/battle/skill/sub_seq.narc	sub_seq_26.bin	0x50	02

Heatproof halves the normal damage done from the Burn status. The battle logic calculates the reduced burn damage by dividing the normal burn damage by an explicitly defined value, in this case 2.

As an example, to change the divisor from 2 to 1 (effectively changing Heatproof to have no impact on burn damage), change the byte from 02 (2 in decimal) to 01 (1 in decimal). Alternatively, you can use a larger value to increase the reduction of burn damage (e.g. change the byte to 04 to divide the burn damage by 4). Make sure to pack the NARC after saving the file.

Quick Feet Speed Multiplier

Sources and Credits: Plat Decomp (1, 2), HG Decomp (1, 2)

Open the relevant file and go to the provided offsets:

Game	File	Offset (Battler 1 Multiplier)	Vanilla Byte	Offset (Battler 1 Divisor)	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x185AE	0F	0x185B2	0A
Platinum	Overlay 16	0x17FAE	0F	0x17FB2	0A
Diamond/Pearl	Overlay 11	0x16EAA	0F	0x16EAE	0A

Game	File	Offset (Battler 2 Multiplier)	Vanilla Byte	Offset (Battler 2 Divisor)	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x1875A	0F	0x1875E	0A
Platinum	Overlay 16	0x1815A	0F	0x1815E	0A
Diamond/Pearl	Overlay 11	0x17010	0F	0x17014	0A

You can also search for these bytes instead

Game	Battler 1	Battler 2
HeartGold/SoulSilver	0F 20 70 43 0A 21 A2 F6 96	0F 20 60 43 0A 21 A2 F6 C0
Platinum	0F 20 70 43 0A 21 8F F6 40	0F 20 60 43 0A 21 8E F6 6A
Diamond/Pearl	0F 20 70 43 0A 21 A7 F6 0C	0F 20 60 43 0A 21 A7 F6 5A

Quick Feet increases the Pokémon's Speed by 50%. The battle logic calculates the increased Speed by multiplying and dividing the Pokémon's Speed by explicitly defined values, in this case 15 and 10, respectively.

As an example, to change the boost from 50% to 70%, change the byte at the multiplier offsets for both battlers from 0F (15 in decimal) to 11 (17 in decimal).

Slow Start Stat-Reduction Duration

Sources and Credits: Chritchy, Plat Decomp (1, 2, 3, 4), HG Decomp (1, 2, 3, 4)

Open the relevant file and change the bytes at the provided offsets:

Game	File	Offset 1	Offset 2	Offset 3	Offset 4	Vanilla Byte (All Offsets)
HeartGold/SoulSilver	Decompressed Overlay 12	0x185E2	0x1878E	0x1C2A8	0x1FA38	05
Platinum	Overlay 16	0x17FE2	0x1818E	0x1BCB0	0x1F440	05
Diamond/Pearl	Overlay 11	0x16EDE	0x17044	0x1AAA8	0x1E050	05

You can also search for these bytes instead

	Offset 1	Offset 2	Offset 3	Offset 4
All Games	05 28 00 DA 76	05 28 00 DA 64	05 28 0D	05 28 03

Slow Start lasts for 5 turns whenever the Pokémon is switched into battle. As an example, to change the duration from 5 turns to 4, go to each offset listed and change the byte from 05 (5 in decimal) to 04 (4 in decimal).

Rain Dish End-of-Turn HP Restoration

Sources and Credits: Lhea, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0xA46C	10
Platinum	Overlay 16	0xA244	10
Diamond/Pearl	Overlay 11	0x98D4	10

You can also search for these bytes instead

	Vanilla Bytes
All Games	10 21 80 59

Rain Dish restores 1/16^th of the Pokémon's max HP. The battle logic calculates the HP restoration amount by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change the HP restoration from 1/16^th of the Pokémon's max HP to 1/10^th, change the byte from 10 (16 in decimal) to 0A (10 in decimal).

Reckless Damage Multiplier

Sources and Credits: Yako, Plat Decomp (1, 2, 3, 4, 5, 6), HGSS Decomp (1, 2, 3, 4, 5, 6)

Reckless increases the power of moves that have recoil or crash damage by 20%, except Struggle. The battle logic calculates the increased damage by multiplying and dividing the move's power by explicitly defined values, in this case 12 and 10, respectively.

However, the multiplier value is explicitly defined across six individual move effects that involve recoil or crash damage in the vanilla Pokémon games. This means six edits are needed to effectively change Reckless' damage multiplier.

Unpack the following NARCs, open the six specified files, and change the bytes at the provided offsets. Make sure to pack the NARC after saving all the files.

1) Crash Damage if Move Misses (Hi Jump Kick, Jump Kick)

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/3/0	0_45.bin	0x20	0C
Platinum	/battle/skill/be_seq.narc	be_seq_45.bin	0x20	0C
Diamond/Pearl	/battle/skill/be_seq.narc	be_seq_45.bin	0x20	0C

2) 25% Recoil Damage (Take Down, Submission)

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/3/0	0_48.bin	0x20	0C
Platinum	/battle/skill/be_seq.narc	be_seq_48.bin	0x20	0C
Diamond/Pearl	/battle/skill/be_seq.narc	be_seq_48.bin	0x20	0C

3) 33% Recoil Damage (Double-Edge, Brave Bird, Wood Hammer)

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/3/0	0_198.bin	0x20	0C
Platinum	/battle/skill/be_seq.narc	be_seq_198.bin	0x20	0C
Diamond/Pearl	/battle/skill/be_seq.narc	be_seq_198.bin	0x20	0C

4) 33% Recoil Damage, Chance to Burn, and Thaws the User (Flare Blitz)

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/3/0	0_253.bin	0x20	0C
Platinum	/battle/skill/be_seq.narc	be_seq_253.bin	0x20	0C
Diamond/Pearl	/battle/skill/be_seq.narc	be_seq_253.bin	0x20	0C

5) 33% Recoil Damage and Chance to Paralyze (Volt Tackle)

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/3/0	0_262.bin	0x20	0C
Platinum	/battle/skill/be_seq.narc	be_seq_262.bin	0x20	0C
Diamond/Pearl	/battle/skill/be_seq.narc	be_seq_262.bin	0x20	0C

6) 50% Recoil Damage (Head Smash)

Game	NARC to unpack	File	Offset	Vanilla Byte
HeartGold/SoulSilver	/a/0/3/0	0_269.bin	0x20	0C
Platinum	/battle/skill/be_seq.narc	be_seq_269.bin	0x20	0C
Diamond/Pearl	/battle/skill/be_seq.narc	be_seq_269.bin	0x20	0C

Item Held Effects

Leftovers End-of-Turn HP Restoration

Sources and Credits: Lhea, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset (Leftovers)	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x1D508	10
Platinum	Overlay 16	0x1CF10	10
Diamond/Pearl	Overlay 11	0x1BD2C	10

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	10 21 FE F7 D5
Platinum	10 21 FE F7 D1
Diamond/Pearl	10 21 FE F7 E7

Leftovers (specifically the item held effect assigned to Leftovers in vanilla Pokémon games) restores 1/16^th of the Pokémon's max HP. HP restoration for this item held effect is determined in the battle logic instead of the item's properties (meaning changing those values in DSPRE's Item Editor has no impact), and is calculated by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change end-of-turn HP restoration from 1/16^th of the Pokémon's max HP to a whopping 1/2^th (for testing purposes, of course), change the byte from 10 (16 in decimal) to 02 (2 in decimal).

Black Sludge End-of-Turn HP Restoration

Sources and Credits: Lhea, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset (Black Sludge)	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x1D548	10
Platinum	Overlay 16	0x1CF50	10
Diamond/Pearl	Overlay 11	0x1BD6C	10

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	10 21 FE F7 B5
Platinum	10 21 FE F7 B1
Diamond/Pearl	10 21 FE F7 C7

Black Sludge (specifically the item held effect assigned to Black Sludge in vanilla Pokémon games) restores 1/16^th of a Poison-Type Pokémon's max HP. HP restoration for this item held effect is determined in the battle logic instead of the item's properties (meaning changing those values in DSPRE's Item Editor has no impact), and is calculated by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change end-of-turn HP restoration from 1/16^th of the Pokémon's max HP to 1/10^th, change the byte from 10 (16 in decimal) to 0A (10 in decimal).

Black Sludge End-of-Turn Damage for Non-Poison Types

Sources and Credits: Lhea, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x1D570	08
Platinum	Overlay 16	0x1CF78	08
Diamond/Pearl	Overlay 11	0x1BD94	08

You can also search for these bytes instead

	Vanilla Bytes
All Games	08 21 FE F7

Black Sludge (specifically the item held effect assigned to Black Sludge in vanilla Pokémon games) damages 1/8^th of a non-Poison-Type Pokémon's max HP. Damage for this item held effect is determined in the battle logic instead of the item's properties, and is calculated by dividing the Pokémon's max HP by an explicitly defined value, in this case 8.

As an example, to change the end-of-turn damage from 1/8^th of the Pokémon's max HP to 1/16^th, change the byte from 08 (8 in decimal) to 10 (16 in decimal).

Move Effects

Aqua Ring End-of-Turn HP Restoration

Sources and Credits: Lhea, Fantafaust, Lmaokai, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x1257A	10
Platinum	Overlay 16	0x11FB2	10
Diamond/Pearl	Overlay 11	0x11252	10

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	10 21 09 F0 9C
Platinum	10 21 09 F0 80
Diamond/Pearl	10 21 08 F0 54

The move effect assigned to Aqua Ring restores 1/16^th of the Pokémon's max HP. The battle logic calculates the HP restoration amount for this move effect by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change the HP restoration from 1/16^th of the Pokémon's max HP to 1/10^th, change the byte from 10 (16 in decimal) to 0A (10 in decimal).

Binding Moves End-of-Turn Damage

Sources and Credits: MrHam88, Lhea, Paille92, Lmaokai, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x12852	10
Platinum	Overlay 16	0x1228A	10
Diamond/Pearl	Overlay 11	0x11528	10

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	10 21 09 F0 30
Platinum	10 21 09 F0 14
Diamond/Pearl	10 21 08 F0 E9

The move effect assigned to binding moves such as Bind, Fire Spin, and Whirlpool, deals 1/16^th of the Pokémon's max HP. The battle logic calculates the damage for this move effect by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change the damage from 1/16^th of the Pokémon's max HP to 1/8^th (matching Gen VI onwards), change the byte from 10 (16 in decimal) to 08 (8 in decimal).

Binding Moves Duration

Sources and Credits: MrHam88, Yako & DarmaniDan, Plat Decomp, HG Decomp

Unpack the relevant NARC, open the specified file, and change the byte(s) at the provided offset(s):

Game	NARC to unpack	File	Offset (Maximum Addend)	Vanilla Byte	Offset (Base # of Turns)	Vanilla Byte
HeartGold/SoulSilver	/a/0/0/1	1_58.bin	0x38	03	0x3C	03
Platinum	/battle/skill/sub_seq.narc	sub_seq_58.bin	0x38	03	0x3C	03
Diamond/Pearl	/battle/skill/sub_seq.narc	sub_seq_58.bin	0x38	03	0x3C	03

The move effect assigned to binding moves such as Bind, Fire Spin, and Whirlpool, lasts 3-6 turns in Gen IV, but effectively traps and deals damage for 2-5 turns. The battle logic (specifically, the subscript called by the move effect for binding moves) calculates the total number of turns through the following process:

1. Generate a random number from zero to an explicitly defined value, in this case 3 (the 'Maximum Addend' or range)
2. Add it to another explicitly defined value, in this case 3 (the base number of turns)

This results in (0 + 3), (1 + 3), (2 + 3), and (3 + 3) as possible outcomes for the number of turns, which effectively traps and deals damage for 2, 3, 4, or 5 turns.

As an example, to change the duration to instead last 5-6 turns (effectively lasting for 4-5 turns, matching Gen V onwards)

1. Change the byte at 0x38 from 3 (3 in decimal) to 01 (1 in decimal)
2. Change the byte at 0x3C from 3 (3 in decimal) to 05 (5 in decimal)

This results in (0 + 5) and (1 + 5) as possible outcomes, effectively lasting for 4 or 5 turns. Make sure to pack the NARC after saving the file.

Another example, but to fix the duration to always be 3 effective turns

1. Change the byte at 0x38 from 3 (3 in decimal) to 00 (0 in decimal)
2. Change the byte at 0x3C from 3 (3 in decimal) to 04 (4 in decimal)

Later in the same file contains the logic for Grip Claw (specifically the item held effect assigned to Grip Claw in vanilla Pokémon games) causing binding moves to always last a certain number of turns.

Game	Offset (Grip Claw Duration)	Vanilla Byte
HeartGold/SoulSilver	0x60	06
Platinum	0x60	06
Diamond/Pearl	0x60	06

As an example, to change Grip Claw to cause binding moves to always last for 7 effective turns (matching Gen V onwards), change the byte at 0x60 from 06 (6 in decimal) to 08 (8 in decimal). Make sure to pack the NARC after saving the file.

Weather

Hail End-of-Turn Damage for Non-Ice Types

Sources and Credits: Lmaokai, Plat Decomp, HG Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0xA42C	10
Platinum	Overlay 16	0xA204	10
Diamond/Pearl	Overlay 11	0x9894	10

You can also search for these bytes instead

Game	Bytes
HeartGold/SoulSilver	10 21 11 F0 43
Platinum	10 21 11 F0 57
Diamond/Pearl	10 21 10 F0 33

Hail damages 1/16^th of a non-Ice-Type Pokémon's max HP. The battle logic calculates this damage by dividing the Pokémon's max HP by an explicitly defined value, in this case 16.

As an example, to change Hail damage from 1/16^th of the Pokémon's max HP to 1/12^th, change the byte from 10 (16 in decimal) to 0C (12 in decimal).

Bug Fixes

Fire Fang vs Wonder Guard

Sources and Credits: Lhea, Shogo Kawada Fan

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 12	0x20BCC	11
Platinum	Overlay 16	0x205D4	11
Diamond/Pearl	Overlay 11	0x1F160	11

You can also search for these bytes instead

	Vanilla Bytes
All Games	11 32 93 42

Fire Fang (specifically the move effect assigned to only Fire Fang) is able to hit through Wonder Guard, even if the target does not have a weakness to Fire-Type moves. More information about the bug can be found on Bulbapedia or searching Fire Fang Wonder Guard on the Kingdom of DS Hacking Discord.

To fix the issue, change the byte from 11 to 10.

Trainer AI Water Immunity Check vs Dry Skin

Sources and Credits: Memory5ty7, DarmaniDan, Lhea, Plat Decomp

Open the relevant file and change the byte at the provided offset:

Game	File	Offset	Vanilla Byte
HeartGold/SoulSilver	Decompressed Overlay 10	0x4DB4	1A
Platinum	Overlay 14	0x4DAC	1A
Diamond/Pearl	Overlay 16	0x1DA7C	1A

You can also search for these bytes instead

	Vanilla Bytes
All Games	1A 00 00 00 26 00 00 00

The Trainer AI performs two checks when considering whether the opposing Pokémon is immune to Water-Type moves. The first check considers Water Absorb, but the second check mistakenly considers Levitate instead of Dry Skin. In practice, this means that (1) a Trainer's Pokémon won't use Water-Type moves if it knows that the opposing Pokémon has Levitate, and (2) a Trainer's Pokémon may repeatedly use a Water-Type move against an opposing Pokémon with Dry Skin.

To fix the issue, change the byte from 1A (26 in decimal, Levitate's ID) to 57 (87 in decimal, Dry Skin's ID).