I'd love to have Tsubomi and AUYuna interact again and I think the battle would be a good place, especially since she's a Red Mage - probably at least help her out enough to get her out of the battle if need be. Just an idea!

As for Sonic, Ha! He doesn't know his own strength and that his actions can cause very bad things. Though Sonic in the Ultima plot... hmm, I could see it. I know I have him in the defense bit, but that one might be a little more useful.