Just wanted to point out a known issue with Silver Surfer that’s present in R83 and will be fixed in a future client patch (although probably not until R85 at earliest, as R84 is already in submission).
Basically, Silver Surfer (and any other 5*) character level appears higher than it actually is when viewed on the pre-battle screen or as a Team-Up. This is a display bug only and the game is treating the level properly. So no, that player isn’t cheating by having a 324 Silver Surfer when it should only add up to 300. It really is a 300, just that the game isn’t displaying the correct variable for level.