Watch Pokémon the Movie: I Choose You! Full Movie
This is the story of how Ash and Pikachu initially satisfied. Initially, Pikachu was disobedient to Ash, however Ash just wished to be buddies with Pikachu. On the day they set out from Pallet Town, both of them saw a Ho-Oh flying and they made a vow to fulfill it.
Director: Kunihiko Yuyama