I think Wario would put up a serious fight, though. If you look at the kinds of things he's capable of in Wario World and Wario Land 4, he might just be one of the biggest challenges for Saitama.
Wario Forums
Boris Carloft's Car Loft
ThAshleyChannel
http://imgur.com/3CvSeqW
Wario wouldn't put a serious fight, Saitama could kill him before it says "Start"
When he fights he let's his foes go first to see if they are powerful enough, in the end he'll one punch anybody. Maybe he'll be a bit impressed with Wario's strength but he won't put up a challenge.
Same with lord Boros, people thought he was a challenge but all it took was one 'serious' punch.
Wario wouldn't put a serious fight, Saitama could kill him before it says "Start"
When he fights he let's his foes go first to see if they are powerful enough, in the end he'll one punch anybody. Maybe he'll be a bit impressed with Wario's strength but he won't put up a challenge.
Same with lord Boros, people thought he was a challenge but all it took was one 'serious' punch.
King Hehehe
He wouldn't really have much of an incentive to fight Wario, though. Wario only really fights pirates and evil entities, and otherwise just keeps to himself, collecting lost treasure or selling video games. Except for when he feels like being a superhero(?). Which isn't often.