Pikachu's Vacation (ピカチュウのなつやすみ, Pikachū no Natsuyasumi) is a 21-minute short movie that is shown before Mewtwo Strikes Back in both the theatrical and the DVD version of the main movie. It is the first of the “Pikachu shorts” in what would be a traditional process of hosting a 20+ minute mini-movie before the main Pokémon feature that would last up until the 6th movie. Pikachu's Vacation, like the five Pikachu shorts that would follow, focuses primarily on an action-packed affair involving solely the Pokémon seen from the anime as they take part in a scenario that eventually illustrates a moral. (Source: Wikipedia)