This article lists Game Genie codes for Pokémon Red and Blue.
GameShark simulator (breaks OAM sprites)
(This is too many cheats for the physical retail Game Genie, so at present it's unknown if this can be done on an actual Game Boy. The code corresponds to 01XXYYZZ from a GameShark and should be used as soon as the game is powered on.)
RNG Plays Pokémon Game Genie version
Make Pokémon Red's title screen say "GreenVersion" (Red only)
Wild encounters are never updated after changing maps
(Can also be used as a 'no encounters' code if started in a building, or an 'old man glitch anywhere' code after watching the old man's demonstration)
Change Pidgey's Pokédex number:
Change Rattata's Pokédex number:
(Replace XX with the Pokédex number in hexadecimal you want. Both can be used to access artificial glitch Pokémon families)
Replace Oak's intro Nidorino:
XX should be replaced with a hexadecimal Pokémon value from The Big HEX List.
'Instant win' every battle
Notes: Similar to Pokémon Gold, Silver and Crystal behavior for having no available Pokémon on the field.
Access Trainer classes:
(XX should be replaced with the desired Trainer class (actual index number or Trainer escape glitch value -200). Artificial Trainer classes are supported)
Sprites aren't filled in properly and look like a painting
Lots of moves do no damage or miss
(The bad poison effect from Toxic is an example of something that still causes damage, so bringing a Pokémon knowing Toxic is useful here)
Metronome move picker:
(Requires a Pokémon that knows the move. XX should be replaced with 01-A4 excluding 76 (Metronome itself). The impossible values 76 and A5-FF, 00 result in a freeze.)
Ghosts don't have ghost sprite and can attack you. Can't attack them:
Battle corruption, if wild battle "invisible battle" mode:
Trainers have Charizard 'M with excessive HP:
Break Pokémon and some Trainer sprites:
Predef commands are broken.
Notes: The title screen intro is skipped, some sprites never load and you start in a Glitch City with no money. You're trapped as well with these orange lines in front of you that makes it look like Red is trapped behind bars. Can't load save data, but doesn't destroy it after you turn off the power and play without this code
Breaks beginning of bank switch function
Notes: Also breaks many sprites and game functions. Text at the beginning of title screen intro is missing as well
Instead of Trainer approach music, the previous music continues to play:
Game Corner slots emote bubble modifier:
(03 and up are glitch emote bubbles)
Base stats modifications
XX must be replaced with the desired base stat in hexadecimal.