I'm ok with any costume, as long as she isn't running around scantily clad. By that I mean, a bikini of any sorts rofl. It's why I generally dislike her C2 and the white variation. It looks wrong on so many levels, to me anyway. Each to their own though.
I'd like to see her in a J-pop idol costume, and a Halloween costume however. I feel if they were to give her an Idol costume, it would be similar to Lei-Fang, Hitomi, Kokoro and Mila's outfits. But they'd probably make the base for it black and white. As for a Halloween costume, admittedly I think it would be hilarious to see her in a similar costume to Jann Lee, but like... a unicorn or something instead of a dragon rofl. A cat onsie... bahaha, she needs a joke costume. With her movelist, you have to admit it would be pretty funny seeing a unicorn or a cat fluttering about with all her spins.
As for a serious costume however, I'm not sure. Maybe some kind of princess costume because she does seem a bit like a princess, in comparison to the other characters anyways.