I don't see how any of them can beat Kun, I have heard the claim that Bane and Vader had greater telekinetic power than Kun, but anyone who read Tales of the Jedi know full well that's a lie.
Well none of these guys are immortal by any means. I'm thinking this battle comes down to whoever manuevers the others into the best position for them to strike them all at once. In that area, Revan wins. But Revan doesn't have the power to beat Vader or Kun. So if Revan can't do it, then Kun most likely would.
I give this battle to Kun. He can engage multiple opponents with his saberstaff and has the power to hold off Vader and Bane.