Mewtwo is number 150 in the original first-generation Pokédex.
Mewtwo appears immediately before Mew, number 151, at the end of the original Pokédex sequence. In the games, Mewtwo is a powerful Legendary Pokémon found late in the adventure, after the player becomes Pokémon League Champion and gains access to Cerulean Cave.
The character also became central to Pokémon: The First Movie, whose Japanese title is Mewtwo Strikes Back. The film explores Mewtwo’s artificial creation and its questions about identity, purpose, and whether a created Pokémon can define its own life.
Mewtwo and Mew are commonly mixed up because their names and lore are closely connected. Mew is the mythical Pokémon placed at number 151, while Mewtwo is the genetically engineered Pokémon at number 150. The numbering is stable across the original National Pokédex order.