Against wario, just stand still and beat his aerial approaches with tilts. Mostly utilt. If he mixes up landing with bite, then walk away and ftilt/needles, if you see him use his second jump feel free to rush him down. Up close use more jabs, this is just generally good vs everyone as Sheik, our jab is the same speed as Peach's and Falco's to give you an idea. Jab cancels lead into virtually anything, against wario I usually just cancel into grab. Jumping at wario is bad, so is being above him. For filling wario, try and use needles when he pulls out the bike, you -can- jump at him offstage and try to do stuff, but that can easily get you killed, because he has superior air control. If you must hit wario with an aerial, bair is your best bet.
When recovering try to use needle cancels to turn yourself around, so that you can use Bair to wall yourself off from gimps.
GR>Upsmash kills at 105.
Ban/strike SV. The moving platform is stupid for him, I'd also strike BF, and force him to pokemon/lylat/FD/Yoshi's.
Halberd is possibly his worst stage in the game, so CP him there.
Stage reasoning: Platforms give wario places to go while airborne, making his already incredibly hard to punish landings harder, the stationary platforms like BF are better for us because the option remains static, the SV platform however is situational but because of that it gets a bit of a surprise factor. Also SV is our second worst starter stage. It's terrible for us, most people only pick it because they're comfortable on it from years of playing on it, but it's not good for us.
Lylat: this one is a bit iffy, it's my personal favorite stage so I'm biased, wario is actually good here so if you aren't completely comfortable with the stage it may not be a good choice.
BF: platforms, GR-Upsmash has to be frame perfect to connect if you release him under a plat, that's annoying but doable, and there's a decent amount of space not underneath plats that you can grab him. It's probably tge most even stage in the MU.
FD: no platforms, we can abuse his landings/get grabs more easily here, wario's generally remove this.
Yoshi's: Wario gets ***** by the middle platform, it ruins his approaches, so just camp under it. Depending on the slant GR>Upsmash might not work, but you can replace the Upsmash with a nair and kill later, or go zelda for kills instead.
Pokemon stadium 1: It's like a play ground, lots of the transformations seal his movements, and we work well with walls.
Halberd: While it's moving he has a platform akin to Yoshi's that ***** his approaches, when it stops moving, he's on an FD with a platform that ***** his approaches. Also a full waft will kill him on the not moving portion of the stage, unless he does it from underneath. Regardless he loses it as an offensive option.