Staying on-topic, I don't mind Fukua hanging around so long as I can easily tell her from Filia whenever they're both onscreen, from the select and loading screens, to the actual fights.
I like the idea of her having an aura, to keep costs low, especially since my idea would be a pain to implement and possibly give everyone a seizure... Making the line-art vibrate all scribbly-scrabbly, like in Ed, Edd & Eddy. Or have a trippy glitchy effect layered on top. Or change colors like Double Rainbow. Or have her be a character that can only be unlocked/used when inputting a secret code.
I'm definitely super biased though, because Robo-Fortune.
I love how diverse the Skullgirls cast is and has the potential to be, and so long as duplicates aren't the norm and not hurting anybody, why take away a character that people are having fun playing with?