Originally Posted by Numinous

I think a third female in the crew would be great. Personality-wise, it'd good to have her somewhat mean-spirited for her own entertainment (like messing around with Zoro and Sanji just to watch them argue with each other even more, or steal Luffy's food just to piss him off), but otherwise loyal to her nakama.

Power-wise,a Logia learning the tricks of the trade, like Dagoro mentioned, would be a good change of pace (it'd be fun for it to be the element of wind, along with great destructive power she could be invisible and have a good excuse for more shenanigans).