I play against Wario a lot :3 Fair stops quite a bit of what he can do in the air, but time it right and dont get predictable. I also use oos Nair after he finishes Dair then grab after. Retreating Nair oos seems to be good cause it lasts for long and can give you space
Lasering is good, gets his % up slowly but surely
Watch out for the fart when you're offstage (or any other time really be aware of it), the Wario I play tries to get me with that and I dont bother to go for the grab release unless I know they mash out of grabs every time. I also shieldgrab a lot if he comes near my shield, pummel a bit then thow down for damage and possible followups (just dont try and grab dair and wait for nair to finish as it has 2 hits)
To get upsmash in when he's above me I watch how he deals with pressure, see if he air dodges and if he does he's toast :D I usually force it by jumping near him like Im gonna attack then fast fall then upsmash..
I have vids/replays that have been saved for the purpose of being uploaded, they will be up one day.. :<