I have a suggestion for a stage.
The stage is Clock Town, from Majora's mask.
The players would fight over the Clock like in the battle against Skull Kid. But on the background, you would see the city during the day, from the point of view from over the clock. The platform would stand still, but the backgound would be moving a bit, each and every second, like the clock is spinning.
Basically, you're fighting on the clock, and the background seems to move as to show the clock is spinning. And you'd be able to see the whole town in a 360 degrees point of view.
Not sure if I was clear enough...
It would be done by making a platform looking like the clock, and making a gif in the background that shows the whole city in a 360° point of view from the top of the clock.
It would be tough, but would be maybe the most incredible stage hack as of now.