Notes:

If the Smash 4 Dr. Mario stage leak is legit, the timing of this is just too good. Check it out here.

This is also hot off the heels of another awesome custom stage made by the same person (ALM5252) called Yoshi's New Island, which has a lot more alternate forms than this stage. Here's a screen of its default form:

EDIT: So it was a fake leak, unfortunately, but hey, we still have this stage for use in Brawl and all of its major mods!