Trouble in Sonic Adventure DX

Hi guys,
So, I've been playing Sonic Adventure DX lately, and I'm kinda confused.
Here's the thing: I destroy Egg Viper and beat the game. I was waiting for Chaos to get giant and destroy the city like the intro shows up, but nothing happened. It's was ok to me, because there are other characters to play, but as soon as I started playing with other characters, I got confused. The story still the same, with minor changes, and I don't think he will get giant again. And here's my question: There's any way to make Chaos bigger (maybe with a emerald that I didn't get or something like that)?

This is what he looks like when he is giant.

You'll have to beat the game with all the characters before you can take on Perfect Chaos. (Like in the intro.) Once you complete the game with each character, Super Sonic is playable and you take on Perfect Chaos.

Thanks a lot! I guess I'm gonna have to experience more bugs to see Perfect Chaos then. XD

Have fun with Big... *cough*

Big isn't so hard to make 100%, but it's so fucking boring...
I hate frogs after this game   
In the end, it all worthed. I was really happy to see that Chaos die. It's a nice game after all.   

Yeah Big's levels are very boring... :\ I usually tend to play through his story as soon as I unlock him to get it out of the way. xD Glad to see that you defeated Perfect Chaos. ^_^