Description from original post (created 2016-04-27 14:44):
Giratina, along with Dialga and Palkia, was created when Arceus hatched from it's egg. Arceus tasked Giratina to create anti-matter. Giratina was known to be one of the most aggressive pokemon. Because of this, Arceus banished Giratina to the Distortion World, where he supposedly would be trapped in forever.