In my opinion Deadpool beats Captain America straight up, if he is serious about the fight. He has done it twice at least.
Deadpool is super underrated, because he tends to fool around a lot and he usually undersells him, because his fights don't showcase his actual physical attributes. He has actual super strength, which was stated and showcased, when he was jumping onto building floors, stopping helicopters from flying away and ragdolling people around.
Deadpool might be able to stop Captain America's shield, even if Cap fully commits to the throw.