Ash meets up with the Mewtwo from Pokémon: The First Movie - Mewtwo Strikes Back (1998) again, while Goh meets it for the first time.
Goh catches a Mankey and a Krabby. Goh also tries to catch a Gyarados, but fails.
Ash and Goh battle Mewtwo and lose.
Mewtwo descending to meet Ash and Goh is a callback to how it descended to face Ash and the other Trainers who gathered on New Island in the first movie.
The introduction to the Pokémon world at the beginning of the episode is a reference of the intro used in the Pokémon movies.