Mewtwo

Mewtwo is a Psychic-type Legendary Pokémon introduced in Generation I. While it is not known to evolve into or from any other Pokémon, it can Mega Evolve into two different forms: Mega Mewtwo X using Mewtwonite X and Mega Mewtwo Y using Mewtwonite Y. It is a member of the Mew duo along with Mew.