If you put Stain in the One-Punch Man universe, you just know he's kill just about everyone.
A lot of the C and B villains would get f*cked up bad
but I don’t think Stain can hang with most of the S class heroes
Genos doesn’t really have blood
Tornado could just force crush him
also Silver Fang would lay him out
He’d be effed if he ran into them lol and god forbid Saitama lol
