Well, I honestly doubt that's Kirby's Stone form. It looks sorta big, and... off. ^^ Not sure what to make of it.
The Spring, though, is from Brawl's Stage Builder. Some Think this may actually be Stage Builder, but with a Kid Icarus theme, though a lot of things goes against that. Maybe it's suppose to act like the Spring Pads from Uprising, but they thought it would make more sense to have actual springs, since they would work the same anyways, as to not seem confusing? Or something? That's my guess.
Source:
http://ift.tt/1mwX08f