Magolor

If Magolor were in Smash Bros., this is what he'd be like.

Well, the only real design change is the addition of a more detailed belt buckle and a belt with holes.

His special moves:

B: Energy Sphere. As in, like the ones used for the Lor (they sorta boomerang back to him).
<-B->: Charge. Like the one he does in his second form, except a lot smaller.
B^: Dimensional Spike. You know how he makes the big spires appear out of the ground? This is where he uses them to propel himself upward. The spikes linger, so if anybody other than Mags touches them they get hurt.
Bv: Fireballs. Three of them spin in his hands before exploding around him. Holding down B/1/whatever button charges the spins. If charged enough they turn orange like Magolor EX's.

The reason he likes Kirby could be interpreted in different ways, like because Kirby is easily manipulated, or just because he's a fan or something.

How would he have a role in Adventure Mode?

...Gee, I dunno. I mean, it'd be cool to have a 2-part homage to Return to Dreamland involving a False Magolor made of Shadow Bugs...

HE CAN'T USE LEG MOVES BECAUSE HE HAS NO LEGS

Kirby franchise (c) Nintendo

EDIT: I just realized that his side-B move is exactly like his catch-up move in Kirby's Dream Collection!