A pit stage from MK could also be pretty fun, although it's likely to be censored in a similar way to the Snes and Genesis without Blood code. I imagine the spikes at the bottom working like Great Cave Offensive, eliminating fighters over 100% and shooting them back upwards if not, although it could also just ko instantly since it's where the blast zone usually is.
Either way, it'd be fun if the Santa Claus easter egg and Blaze fighting in the background were kept, maybe even with an event match where you fight a Green Scorpion on the stage?