Wario:
--Bite is a *****: You're going to get bitten -a lot- if you are not careful here. It acts as a grab and thus has priority over many of your attacks. For instance, if you are standing just out of range of the Bite and you start to jab into it, you'll get caught in it. Keep your spacing and use one of the many disjointed hitboxes at your disposal to counter this (my favorite is Walking --> Fsmash :o ...it's all about predicting). Common approaches I've seen are falling from above on top of your shield and right out of a Dair. Oh, and don't spotdodge this...cause that is just silly.
--Dair is amazing xD: The single move is my bane whenever I play against Wario. Amazing shield pressure combined with Wario's fantastic aerial control make this very hard to get around if Wario knows what he's doing. That's not to say it's impossible, however. Learn exactly when the last hit of Dair comes out, so you can drop your shield right away and go for the punish. Keep in mind this will eat your shield if you keep standing there and taking the full hits. If you find this happening, change up the timing of your approaching/retreating.
--Shorthopped Airdodging ruins you: At least it does for me xD. With Ike's naturally laggy attacks, it can prove rather easy for Wario to short hop airdodge right around you. Just be wary of this as a general approach for Wario. All I can say really is try to bait the dodge and punish for it. But that is easier said than done. Nair does pretty well at punishing dodges, especially if he likes to airdodge behind you.
--Your range > his: This is self explanatory. Use this to your advantage in this matchup. Just be careful of the shorthopped airdoge approach. That should do here...
--Grab Jump Break --> Uptilt: Should be known by now, but in case you don't, grabbing Wario and getting him to jump break(not pummeling him) will combo into Ike's uptilt. It sets up for an auto KO at the right percent. Just be aware that this is an option.
--Sure his recovery is good, but...: If you can catch a Wario without his bike, forcing him to corkscrew back up to the ledge, spike his ***. Corkscrew doesn't sweetspot the ledge, so feel free to use whatever method you feel appropriate :D
--Don't get gimped: He's got the ability to gimp you by throwing out a few aerials off the stage and use the bike to get back. Just be wary, timing airdodges and the like.
Misc. Notes:
-Half charged farts kill you, don't let them.
-Grabs work well in this matchup, use them.
-Ground stalking is less useful due to Wario's great aerial control, but that doesn't mean you shouldn't be doing it.
-Uair ****, watch out for it...it kills :o
-His Fsmash is fast, but laggy after the hit.
-Your Fsmash is awesome, use it :D
That be it for now.