The game was originally due out for Switch alongside an Xbox One version this past spring. A Microsoft Store listing for the Xbox One version has yet to surface, so are currently unable to confirm whether the Xbox One version is due out on the same date, but we have sent an e-mail to publisher Skybound Games and are awaiting a response.
Here is an overview of the game, via Nintendo.com:
Skullgirls 2nd Encore is finally available to play on the go on Nintendo Switch! It is a beautiful, fast-paced, and critically acclaimed 2D fighting game that puts players in control of fierce warriors in an extraordinary Dark Deco world. Each of the 14 wildly original characters features unique gameplay mechanics and plenty of personality.
Skullgirls 2nd Encore is the perfect fighting game for casual and competitive fighting game fans alike. Includes fully voiced story mode, gorgeous animation, and a soundtrack by Michiru Yamane.
Update 10/17/19 at 9:42 p.m.: The Xbox One version has been “postponed indefinitely,” according to the publisher. Read more here. Watch a trailer for the Switch version below.