I would say it is less about the special moves, you look at the normal combos, a lot look very similar. I think the problem is all the Saiyan characters are just going to naturally be similar, which is a large part of the cast. Even
Max mentions it in his reaction video to Nappa, he has been nothing but positive about the game, but you can see he is disappointed that Nappa moves the same to everyone else. I have to say Android 16 is the one character I have locked in to play so far.
Also IGN should be showing off another 2 characters next week, they are really pumping these out now