Pocket Monsters Diamond & Pearl: Giratina to Sora no Hanataba Sheimi

A hidden dimension called the Reverse World exists as a mirrored counterpart to the known world, home to the legendary Pokémon Giratina. A conflict arises between Giratina and another legendary Pokémon, Dialga. The reasons behind their battle and the nature of the Reverse World remain unclear. During their travels, Satoshi and his companions encounter the small and playful Pokémon Shaymin, which is connected to the conflict between the two powerful Pokémon. An unforeseen event occurs to Shaymin, prompting Satoshi and his group to work with it in an effort to end the battle and prevent harm to both worlds.