Well,
The only thing I usually be aware of is his Fair (damage racking) and Uair (For the kill). We don't really have too much problems on this matchup If Ness starts brickwalling against you just attack properly from above and you should be fine, careful with his Uair on killing perents while trying to approach from above also, IT KILLS, believe me. I recommend you to save FSmash for a GR > FSmash near the edge that could kill Ness at 90%.
Ness's Bair wont be fresh though he'll use it for approach sometimes and to rack some damage too and, if you DI it properly you'll survive at abnormous %s.
About recoveries, DO NOT recover from below, his dair will **** you up in both ways, sweetspotted or sourspotted, it'll knock you of the bike suficiently to mess up your UpB, but I believe no Wario is doing that. About his recovery, gimp city, fart, fair, nair, bair, bite, just land whatever you want to mess it up, when he uses his upb he just got a little lag after doing the whole movement to recover so gimp him while he's trying to do it.
I believe it's 60-40 Wario tending to 65-35.