Fan Casting Arceus in Celebrity Guest Stars in Pokemon Movies

Arceus debuted in Arceus and the Jewel of Life. It was angry at the people of Michina Town for Damos's unwitting betrayal of it in ancient times, and so it attempted to destroy the world. When Ash, his friends, and Sheena were teleported by Dialga to ancient times, they directly influenced the event, changing the future for the better so that Arceus will stop its destruction.