Giratina is a major character from Giratina and the Sky's Bouquet: Shaymin and it's confirmed that Giratina will be in the 12th Pokémon Movie.
In the movie, Giratina is the only pokémon that lives in the Reverse World. For the battle between Dialga and Palkia in The Rise of Darkrai, the habitat of Giratina absorbes all the pollution of the battle, so Giratina looks Dialga and Palkia as enemies. In a lake in the Real World, Giratina lured Dialga to the Reverse World, hoping revenge. But Dialga escapes, and later, Zero catches Giratina, hoping to copy Giratina's abilities. Giratina almost die, but is healed by Shaymin. Giratina, with Shaymin and Ash defeat Zero, and save the Reverse World.
At the end of the movie, Giratina looks for Dialga again.
In the teaser of the 12th Pokémon movie, Giratina, Dialga and Palkia are all they ready to battle.
