Shelton - better fighter and has a better toned athletic body
Harcore - The name says it all, you can tell in the eyes this guy can start and end a fight.
In their prime -> Stone Cold as his character is a reflection of what he really is, a guy who dont take crap from someone, and if your someone like that, you got to back your words with actions, and I think that he could take the fight to the next level if needed.
Hard to pick but depends on the scenario, cos Road Warrior could charge and break him apart, but Flair could live up to his reputation and for example have dust in his hands and blind the animal.
Kurt Angle would win just about any fight as physically quite strong and athletic enough to perform the submissive moves on anyone.
Booker is the man no doubt