Mewtwo’s National Pokédex number in the Pokémon video game series is 150.
Mewtwo is a Psychic-type Legendary Pokémon introduced in the first-generation games. It appears immediately before Mew, which holds National Pokédex number 151, making the pair especially important to the original Pokédex sequence.
In the games’ story, Mewtwo is associated with genetic experimentation based on Mew. It is portrayed as an exceptionally powerful Pokémon created through scientific manipulation, and it became a major legendary encounter near the end of the original games.
Mewtwo’s number is sometimes confused with Mew’s because the two names and their story connection are closely linked. Mewtwo is not the final entry in the original National Pokédex: that position belongs to Mew. Later games also introduced Mega Mewtwo X and Mega Mewtwo Y, but both remain associated with species number 150.