Mewtwo was created by cloning Mew in Pokémon lore. Scientists used genetic material from the Mythical Pokémon Mew to create a powerful engineered Pokémon.
The backstory is presented in games and animated adaptations with some differences. In the first Pokémon games, Mewtwo is described as the result of experiments involving Mew’s genes. The Pokémon is associated with Cerulean Cave after escaping from the laboratory where it was created.
The first Pokémon movie develops the story further. In that film, scientists working for Team Rocket create Mewtwo as a genetically engineered supersoldier. Mewtwo eventually rejects its creators and questions whether its origin determines its identity or worth.
Mewtwo is not simply an evolved form of Mew. They are separate Pokémon species with different Pokédex entries, designs, abilities, and battle statistics. Mew is a small Mythical Pokémon said to contain the genetic structure of all Pokémon, while Mewtwo was intentionally produced through scientific experimentation.