I wouldn't mind it, to be honest. Skins shouldn't add any stats, they should be purely aesthetic changes. I think that Tentacruel one posted above is really something. Things like taht would be so cool. I don't see the devs adding any to the game, but it wouldn't hurt.
I would actually like some more colour combinations. Black and white would be cool to see, but they're not very colourful so I can't imagine those colours will be added. Correct me if I'm wrong, but I don't think red has been used yet so that could be paired up with something. Dark green? A light purple? I'm not sure what would work with it but I'd like to see a big variety of colours.