
In the film, Arceus, a powerful creature known as a Pokémon, awakens from a long slumber to seek justice on the humans that refused to return Arceus its life-giving jewel and attacked it. Through loop quantum cosmology, the spacial distortions caused by Arceus's awakening leads to the conflict between the extradimensional Pokémon Dialga, Palkia, and Giratina. To prevent Arceus from attacking humanity, Dialga sends Pokémon trainers Ash Ketchum, Dawn, and Brock back in time, along with Sheena, a descendant of the man mistakenly believed to have betrayed Arceus.