Ereiam 
"[@Evil Emperor Proteus":](/1100981#comment_5827462
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You forget one big thing: Saitama is a parody character. His strength has no discernible upper limit and he always easily defeats his opponents as soon as he can reach them (which, due to his poor sense of orientation and limited awareness to his surroundings, can sometimes take a while - which the threat takes advantage of to steamroll every other hero standing on its way - until Saitama reaches it or stumbles upon it, at which point he inevitably curb-stomps it).
He's immune to physical attacks, psychic abilities, and I wouldn't be surprised if he could no sell magic or reality warping as well. Similarly to psychic power, his dense mind also makes him impervious to mind games. When a villain takes too long with his gloating monologue, Saitama's reaction is to cut them off, either with a flippant demand to get on with it or with a punch (the outcome is the same either way).
And on top of that, we're supposed to believe that his abilities come from having followed some mildly intense daily workout routine (the explanation given in the webcomic is a bit more than that, but so far, it still boils down to "just because" indeed), which shows how seriously Saitama must actually be taken.
If you want to pit Saitama against a character from the Marvel Universe, I think the most sensible match against him would be Deadpool (despite not having Saitama's overwhelming strength, he has a nigh-unbeatable healing factor, is pretty resourceful, also kind of a joke character himself and enough of an anti-hero to give Saitama probable cause to fight him).
In any case, Saitama would undoubtedly be eager to fight someone who can take his serious punches and get back on his feet, and Deadpool would probably be curious to see if Saitama can punch him hard enough to break his curse.
Monde de merde
You forget one big thing: Saitama is a parody character. His strength has no discernible upper limit and he always easily defeats his opponents as soon as he can reach them (which, due to his poor sense of orientation and limited awareness to his surroundings, can sometimes take a while - which the threat takes advantage of to steamroll every other hero standing on its way - until Saitama reaches it or stumbles upon it, at which point he inevitably curb-stomps it).
He's immune to physical attacks, psychic abilities, and I wouldn't be surprised if he could no sell magic or reality warping as well. Similarly to psychic power, his dense mind also makes him impervious to mind games. When a villain takes too long with his gloating monologue, Saitama's reaction is to cut them off, either with a flippant demand to get on with it or with a punch (the outcome is the same either way).
And on top of that, we're supposed to believe that his abilities come from having followed some mildly intense daily workout routine (the explanation given in the webcomic is a bit more than that, but so far
If you want to pit Saitama against a character from the Marvel Universe, I think the most sensible match against him would be Deadpool (despite not having Saitama's overwhelming strength, he has a nigh-unbeatable healing factor, is pretty resourceful, also kind of a joke character himself and enough of an anti-hero to give Saitama probable cause to fight him).
In any case, Saitama would undoubtedly be eager to fight someone who can take his serious punches and get back on his feet, and Deadpool would probably be curious to see if Saitama can punch him hard enough to break his curse.