The little indie fighter that could, Skullgirls, is coming to mobile devices on May 25. Why this version exists is a little beyond me, but more people playing the underappreciated gem is a good thing. There won't be any exclusive features in this version, apart from touch based controls I would assume.
As to what mobile platforms, neither Game Informer nor the dev blog state any. The game will be launching in North America, South America, Europe, Australia, New Zealand and the Philippines, so you're bound to be able to actually buy it. There isn't a price mentioned, but the regular version goes for $9.99 on PC, so I would guess that. The dev blog does say that other characters will be introduced through updates, so I doubt this is a port of 2nd Encore.
Skullgirls Mobile Arrives May 25 [Game Informer]