Under weaknesses for Superman you need to also mention he is vulnerable to all magic. If you are doing points he wold cost tons as he can do just about anything from hearing a pin drop across the globe to being arguably the fastest hero on Earth on land and in the sky. His hits should be auto kills unless the player decides to hold back for some reason. They would auto penetrate anything as well.
I do allot of superhero stuff and after tons of play testing Sup the only way to really play him with any chance of beating him is it has to be the Golden Age Sup where he wasn't as invincible as the modern day one.
If 10 wounds are your base then Joker should be a 2 and Angel maybe a 5. Batman is one tough SOB so he would be a 9 or 10 and if Sup is wounded a 10 would seem sensible since it would be made of Kryptonite or magic.
Now this is all coming from a comic book freak that has been reading them all for over 30 years so I might be a bit to critical to who the characters really are.
Brian