all star zombie does not have any ammo but a overheating mechanic and his damage upclose is 7 damage (9 damage for critical damages) Scientist zombie is the most fragile character but with a damage upclose with 77 damage and 20 damage in farther ranges and a teleport ability probably might be the best character but not the close its has 5 ammo and a long reload ( 7 ammo for the ammo upgrade)
the best one is probably foot soldier zombie with 10 damage for crits and body shots and 7 damage in long range good reload time and with a rocket launcher ability that has 300 damage a rocket jump ability and a stink grenade he is probably the best zombie for any situation