He WAS a Major antagonist in the series
Meh, I never liked it
I always thought that it was an obvious, unoriginal and uninspired villain
He is just Dark Matter, you can't got farther than Zero Two (well, you actually CAN, but making Zero two look even creepier wouldn't be a good idea, specially in a kirby game)
The same goes for Nightmare, he is really obvious and boring IMO
He look more like some kind of vampire with a giant chin
If we're gonna get more "Darkier and Edgier" antagonists I would prefer the Dark characters from the Mirror World, Dark Meta Knight, Shadow Kirby, Shadow Dedede, etc
Maybe even Darkdana Dee!
I don't really think that the next kirby game will be on the Wii U
Kirby gets his games usually in handheld consoles
The only main kirby game for the 3DS is Kirby Triple Deluxe, It wouldn't surprise me If we get a new kirby platformer this E3