In a chance encounter by a serene lake, Giratina, the legendary Renegade Pokémon, seizes Dialga, the Temporal Pokémon, and drags it into an alternate dimension. However, a small green Pokémon is inadvertently pulled into this realm as well, leading to a chaotic escape. As Dialga flees, disrupting Satoshi and his friends' picnic, the green Pokémon, now known as Shaymin, is rescued and cared for at a Pokémon Center. Shaymin, the mythical Gratitude Pokémon, communicates its urgent need to be taken somewhere by Satoshi, Hikari, and Takeshi. Yet, as they embark on this quest, they find themselves pursued by Giratina and the enigmatic figure Zero, both intent on capturing Shaymin. Can Satoshi and his friends navigate this perilous chase to fulfill Shaymin's wishes and evade the looming threats?