Which Pokémon is National Pokédex number 0150?

Mewtwo is National Pokédex number 0150.

Mewtwo is a Psychic-type Pokémon introduced in Generation I. In the games’ story, scientists created it through genetic manipulation based on Mew. It is portrayed as extremely powerful and as a being whose abilities were produced through experimentation rather than ordinary evolution.

Mewtwo appears near the end of the original Pokédex, immediately before Mew at number 0151. This ordering often causes confusion because Mew is the genetic source described in the story, while Mewtwo carries the number 150 and Mew carries 151. The two Pokémon are related in the fiction but are separate species.

In Pokémon Red, Green, Blue, and Yellow, Mewtwo can be encountered after the main story in Cerulean Cave. Later games gave it two Mega Evolutions, Mega Mewtwo X and Mega Mewtwo Y. Those forms do not change its original National Pokédex number.