Trainer mutation glitch

Select glitches in Japanese Pokémon Red, Green and Blue

Battle disabling Select glitch | Badge describer glitch | Dokokashira door glitch | Fossil conversion glitch | Item creation glitch | Lift glitch | Partial switch glitch | Remaining PP into species Select glitch | Second type glitch | Skip to Level 100 glitch | Trainer mutation glitch | Walk through walls | Warp by Nidoran♂ glitch

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Please note that this glitch only exists in the Japanese versions of the game, or is otherwise a glitch from a Pokémon game which was only released in Japan.

Trainer mutation glitch is a closed menu Select glitch in Pokémon Red, Green, and Pokémon Blue (Japanese).

It allows the player to change what groups of Trainers in a map say, how they turn, and what class they are. If the new 'class' is less than 200 (C8), then they will turn into Pokémon. The player can also change the Pokémon's levels.

Unfortunately the player can't manipulate the species/class of the first Trainer IDs 1-4 in a map unless they have a Pokémon with specific stat experiences (so no 'fresh' Pokémon) but they should be able to manipulate others.

Basic steps

1) Press Select on the 20th item.

2) Exit and go into battle, then swap the 20th Pokémon with a Pokémon of your choice.

3) Without using a warp, go to a Trainer and they should have 'mutated'. Do note that a Trainer's text may freeze the game, and beware of Missingno. in Red/Green.

The game may freeze after the switch with no documented fix.

Technical details

Every Trainer on a map has an ID. This glitch lets you change the Pokémon (or Trainer) and level that a certain Trainer ID is. The ID can be tracked with memory viewer by talking to a Trainer and viewing address CC55, CD4F, or CF0E. As maps have multiple Trainers (and IDs), you can mutate more than one Trainer.

When you switch the Pokémon, you're actually switching the 20th Pokémon with the first. This puts various Pokémon data into unrelated data, and one group causes the Trainer mutation effects.

Original Address	Original Address 1 data	Destination Address	Destination Address data
N/A	N/A	D463	Trainer 01 turning data
N/A	N/A	D464	Trainer 01 text
N/A	N/A	D465	Trainer 02 turning data
N/A	N/A	D466	Trainer 02 text
N/A	N/A	D467	Trainer 03 turning data
N/A	N/A	D468	Trainer 03 text
N/A	N/A	D469	Trainer 04 turning data
N/A	N/A	D46A	Trainer 04 text
N/A	N/A	D46B	Trainer 05 turning data
N/A	N/A	D46C	Trainer 05 text
N/A	N/A	D46D	Trainer 06 turning data
N/A	N/A	D46E	Trainer 06 text
D12B	Species byte 2	D46F	Trainer 07 turning data
D12C	Current HP byte 1	D470	Trainer 07 text
D12D	Current HP byte 2	D471	Trainer 08 turning data
D12E	Level (possibly)	D472	Trainer 08 text
D12F	Status ailment	D473	Trainer 09 turning data
D130	Type 1	D474	Trainer 09 text
D131	Type 2	D475	Trainer 10 turning data
D132	Catch rate	D476	Trainer 10 text
D13F	Attack experience byte 2	D483	Pokémon 1 species
D140	Defense experience byte 1	D484	Pokémon 1 level
D141	Defense experience byte 2	D485	Pokémon 2 species
D142	Speed experience byte 1	D486	Pokémon 2 level
D143	Speed experience byte 2	D487	Pokémon 3 species
D144	Special experience byte 1	D488	Pokémon 3 level
D145	Special experience byte 2	D489	Pokémon 4 species
D146	Attack & Defense DV	D48A	Pokémon 4 level
D147	Speed & Special DV	D48B	Pokémon 5 species
D148	PP of move 1	D48C	Pokémon 5 level
D149	PP of move 2	D48D	Pokémon 6 species
D14A	PP of move 3	D48E	Pokémon 6 level
D14B	PP of move 4	D48F	Pokémon 7 species
D14C	Pokémon level	D490	Pokémon 7 level
D14D	Max HP byte 1	D491	Pokémon 8 species
D14E	Max HP byte 2	D492	Pokémon 8 level
D14F	Attack byte 1	D493 (unconfirmed)	Pokémon 9 species
D150	Attack byte 2	D494 (unconfirmed)	Pokémon 9 level
D151	Defense byte 1	D495	Pokémon 10 species
D152	Defense byte 2	D496	Pokémon 10 level

Example

Let's say you want specific Pokémon for Trainer IDs 02 through to 07 as such.

ID 02: Level 1 Mew ID 03: Level 254 Mewtwo ID 04: Level 5 Articuno ID 05: Level 5 Zapdos ID 06: Level 5 Moltres ID 07: Level 100 Porygon

This would require the following data from address D141:

15 01 83 FE 4A 05 4B 05 49 05 AA 64

And that is:

• Defense experience is 21 modulo 256.
• Speed experience is exactly 387.
• Special experience is 65098.
• Defense DV is 5, Attack DV is 0.
• Speed DV is 11, Attack DV is 4.
• Move 1 PP is 5.
• Move 2 PP is 73.
• Move 3 PP is 5.
• Move 4 PP is 42 w/2(?) PP Ups used.
• Pokémon is level 100.

Those requirements are totally unviable for non-cheat play, so it's a proof of concept, but you can get cool results with random Pokémon.

YouTube video

YouTube video by ChickasaurusGL

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