I am very dangerous with Onion Kid. Since all his brave attacks chain to HP, if I get you with one hit you are at my mercy. I mainly hit and run with him, and it's quite effective.

I also play Ultimecia a lot lately, with her I'm always attacking and keeping distance. Build up EX, then stop time and fire an HP attack for an EX burst. Takes a long time to pull off but it's almost impossible to hit her with most characters.