This one is a bit tougher. I am leaning towards Ness.
It shouldn't be Wario. His recovery is incredible, and so is his Forward Smash. Also, his B moves don't really help against projectile spammers. His bite can eat junk like grenades, yes, but with the moves you would SPAM (lasers, arrows, Din's Fire, etc.), he cannot eat ANY of those.
Wario is completely debunked. It should not be Ganondorf or Falcon, unless their Down B's can cancel out some projectiles (which they probably do with Samus missiles and Peach turnips, but that's probably it). Maybe if they also cancel out Din's or arrows, or if Falcon's forward B can do that...
Otherwise, it isn't them. It isn't Ike because Ike has options on the ground.
Well actually it COULD be Ike since he has good aerial strength and his ground moves are a bit harder to land. And his recovery can be gimped. The semi-anti-spam B moves could also either be forward B or down B.
Ooooh and Bowser... I just realized this. He does kill well, however, his B move that would help a little against projectiles would be Fortress. However, that and his f-tilt give him a decent enough ground game.
So in conclusion it is probably Ness or Ike. Maybe Bowser.
Edit: About Luigi, it would be his fireballs as his B move. His aerials are ridiculously good and a lot better than his ground game, however his ground game isn't bad at all either. Also, his recovery is more on the punishable side than the gimp side. Hard to gimp him, but a lot easier to punish.
I'm still gonna stick with it being either Ness, Ike, or maybe Bowser.