………Unless of course, those mentioned "rules" are of something we don't know of yet. This is just one image, after all. So who knows.

Seeing how there are Minecarts, this might be a travelling stage, and since it's from Kirby Super Star, it might be a travelling stage that goes to different parts from the game. So we'll just have to wait and see.

That's Old tower. Not Mt. Dedede.
Unless the Tower of Smash leaker messed up and mixed up the tower with DeDe’s castle, or this is a traveling stage……. I dunno.