Yeah you can use any combo as long as there is no weapon equipped. Try using Zombait and an Untouchable mixed drink. That way zombies will swarm you but won't be able to grab you. The two most useful moves were the Elbow drop and Power Bomb...both kill multiple enemies at a time.
you need to get in a glitch or just on the ps3 you can freeze up in the air by turning off your controller and just float but you really could not do that cause you need to kill them but thats an easy way to get to round 1000 on W@W zombies