To find identifiers (the value for '??' or 'xx') for glitch Pokémon, items, moves or letters, use the Big List. Users are welcome to put these in the code archives too.
Please report any broken codes on the respective article's talk page, or on the forums.
Pokémon Red, Green, Blue and Yellow (JP) GameShark codes Pokémon Red, Blue and Yellow GameShark codes Pokémon Gold and Silver (JP) GameShark codes Pokémon Gold and Silver GameShark codes Pokémon Gold and Silver (KO) GameShark codes Pokémon Crystal (JP) GameShark codes Pokémon Crystal GameShark codes Codes from Pokémon games later than Generation II are currently not allowed.