Kanto Expansion Pak

Kanto Expansion Pak is a ROM Hack that aims to remain faithful to core Generation 1 mechanics and the competitive metagame revolving around it, while also including scrapped and new content to the game. This includes adding in new and "returning" Pokémon, trainers, and music, alongside the return of unused Super Gameboy Palettes.

Scrapped Pokémon from the leaked beta versions of Red and Green (and some from the leaked Gold and Silver beta versions) were added back to the game alongside Pokémon that are related to Kanto or Pokémon from Kanto; this includes the Melmetal line, regional forms of Generation 1 pokemon, evolutions from Generation 1 Pokémon such as Magmortar, and the paradox Pokémon of Scream Tail and Sandy Shocks. The original beta renditions of the Dark and Steel type have been added, as well as the original beta Fairy type.

No prexisting Pokémon received changes such as typing changes from later generations, to keep the game to feel authentic a possible and to have new Pokémon be additional to the Generation 1 metagame rather than to supplant Pokémon like Snorlax, Chansey, and Tauros.