Though she's not released yet, Krystal was revealed as a fighter in 2018. The creators, McLeodGaming, are still working on the game, preparing its next release with tons of new characters and features, so unfortunately, Krystal isn't available yet.
In the meanwhile, however, the team has revealed a new stage from Star Fox Adventures: Krazoa Palace. In this stage, there are two floating platforms, and an optional hazard fan that gently levitates the fighters above it. You can see Fox and Krystal on the stage here.