My general idea for that was as follows
1)Chaos 0 dissapears
2)Perfect Chaos raises but slightly behind the stage.
3)Perfect Chaos flails his head around biting parts of the stage.
4)Perfect Chaos Sinks back down and dissapears.
5)Chaos 0 re-appears where where he dissapeared.
i like that also u should have the chaos emeralds that he adsorbs like sonic dx