Stallone actually beat Creed in a boxing match whereas the Governator could only manage a "manly" handshake against him, therefore by virtue of triangle logic, Stallone wins
Since neither has any boxing skill I'll go with Arnie on account of his weight advantage. I'dfancy De Niro over Stalloe too, he as apparently quite handy.
I got Sly in this one. Think he'd wear Arnie down. Pummell him to the body. Arnie would only be able to push him off. Rocky style baby