If the stages are in both the 3DS and Wii U version, why wouldn't we see them? We've got all the stages that happened to have been confirmed cross-system like Wily's Castle and Boxing Ring, yet nothing else familiar is there? It just so happens to give us stages like those for the ones we already know about...? That's a red flag right there.
Even if we don't have every stage unlocked, that still doesn't explain why Kirby, Sakurai's child and a series with plenty of steam as of late, would only be regulated into being a cameo of a Nintendo system and not have something from Kirby Triple Deluxe, Kirby Super Star Ultra, or Kirby Mass Attack to be in the starting roster of stages. If any series was going to have a new stage, Kirby would be one of them. Two strikes.
I know we're starved for "The End" of all this speculation, but there's much more reason to believe this is fake than there is reason to give it more than one glance.
Hm? I was not aware. My mistake. The point stands that there's no reason to believe Game Boy would be our one Kirby stage beyond two Kirby characters standing on a blank screen.