Pokémon : Fire Red Delta

Pokémon FireRed Delta is a difficulty/fakemon ROM hack with the goal of replacing 149 of the 151 gen 1 Pokémon with freshly designed Delta variants. Mew and Mewtwo are excluded from the redesign due to their postgame nature.

All 149 of the Delta variants are accessible before defeating the Elite Four, and all trade evolutions have been replaced. “Pick one” type Pokémon, (e.g. starters, fossils) have been added to Altering Cave in the Sevii Islands postgame. The game is fully complete and playable to postgame.

Source: TheGamesDB