To quote Scar "when it comes to strength I'm afraid I'm on the shallow end of the Gene pool". Mufassa and Simba can beat Scar no doubt about that. Shere Khan however? Undisputed king of the Jungle Book Universe. Only beaten through dumb luck is and one of the only Disney villains to not die or be captured. Shere Khan should be able to beat either Simba or Mufassa.
This is an incredibly close fight. Gotta give it to Team 2. If Scar can hold off either his brother or Simba for a bit(which he surely can) he can hold them long enough for Shere Khan to come in and make it a 2 on 1 fight which is impossible for Team 1 to win.