Tertec: Starlight Saga
The Legendary Pokemon of antimatter, sole inhabitant and guardian of the Distortion World, and Judge of the Ghost World.
It was originally banished outside of all dimensions by Arceus for chaotic, destructive behavior, but it eventually grew the Distortion World around itself and suppressed it’s rebellious spirit deep within (exists as an item called the Renegade Wing). It then took up it’s current mantle of Judge and Keeper.
Giratina is now characterized by a desire to protect the other dimensions behind the material world and thusly also by a sense of order. It has an understanding of human communication that is unusual among it’s peers. Although contact is exceedingly rare, Giratina is very straightforward in giving information to humans.
The Pokemon is tied to the material world by the Griseous Orb, whose holder can feel it’s presence and communicate with it. It also has portals in a scant few locations which usually remain inactive. When it is required in the material world it very rarely manifests completely, instead choosing to appear as a shadowy being that “oozes” from it’s portal. This ensures that nobody can cross over unnoticed and allows Giratina to keep drawing power from it’s home dimension.