If memory serves, the only reason Cyrus doesn't destroy the universe by unleashing and taking control of Dialga and Palkia's powers (Dialga controls time, Palkia controls space) is because in doing so he also awakened

THIS.

Giratina, a Pokemon whom I can only describe as (Lucifer + Cthulhu)^Chara.
Fair warning, the very end of the video may freak you out a bit due to some mild Interface Screwing.