Wario's definitely a pain when he gets in. I've said this before, but Wario can really mess you up if you don't respond to one of his mix-ups correctly. If you can stop him from gaining momentum, you can swat him away with FAirs and Klaw. He doesn't really have the range to compete with Bowser's giant turtle arms, so keeping him out is your biggest priority. I'm sure you know this, but Wario likes to flutter
just outside your range a la Jigglypuff, and wait for you to do something. It's his unique brand of aerial dash-dancing that makes fighting him so frustrating. One of the things that I use to a decent effect as Wario is FF Bite. I can't stress enough the fact that you want to avoid Bite at all costs. When The Fat Man starts getting it consistently, you'll find yourself in more and more bad situations. Wario also gimps like a madman, and you want to watch out for NAirs/FAirs offstage, they'll take your stock like that. Fortunately, his recovery is very mediocre, and hitting him after he's used his jump usually seals the deal.
I'm tired and don't feel like typing anymore stuff, but I'd definitely pop into that thread if you decide to make it. I'll also try to play a bunch at Zenith to further expand my MU knowledge. Hope I helped!