Mewtwo is a modified clone of the Pokemon Mew. The scientists who created it dreamed of making the strongest Pokémon ever that in return destroyed it creators. So far in the anime and mangas there has been only one in existence.
Mewtwo is a modified clone of the Pokémon Mew. It was created by extracting DNA from a Mew fossil. The scientists' goal was to create the most powerful Pokémon the world had ever seen.