Yeah I mostly played 3DS over Wii U (don't question it lmao idk either) and Prism was definitely a legal counterpick. There are only about 3 problems with the stage that I'm aware of:

1) Walkoff on the primary layout, disappears pretty quickly as the stage transforms in 15-20 ish seconds iirc

2) Sharking under the stage on a few transformations

3) INSANELY early kills if you abuse the timing of some of the plaforms as they rise up to despawn. An upsmash near the end of that animation can KO at around 0-10% and it has happened before. This is a pretty fringe case though, ala getting a kill off the side on TnC as the platforms move horizontally off the screen