This is the main original title for the Pokémon film commonly associated with Mewtwo's story and its sequel/alternate releases. It is the first theatrical Pokémon movie, centered on Mewtwo and the conflict surrounding its creation and identity. The title is widely used in English-language releases and is the most recognizable master title for matching related variants. If you are looking for the broader franchise entry rather than a specific re-release or subtitle variant, this is the standard base title.