I think we can all agree the battle mode in MK8 is severely hampered by the long courses. However, for the first time Nintendo can add courses as DLC (and I'm fairly certain they will).
So what I'm wondering is: what kind of stages do you want to see? These can be older ones, ore ones you made up. They could even be from other games.
My list:
Nintendo Gamecube (Double Dash): a nice compact stage with no place to hide
Block City: Still compact but with some places to hide
Ghost mansion (Nintendoland): Focus is more on a mazelike hide-and-seek for people to hide from and hunt each other
Battle planet (new): taking advantage of antigravity, takes place on the surface of a sphere, with or without some obstacles
Ghost mansion (new): takes place inside effectively a cube with a bunch of different rooms and nearly all the walls and roofs of each room being antigravity. could also be themed after a ? Block.