Personally I think limiting them is a waste of time and too hard to judge. Perhaps add more of the powered and limit them to 1 or 2 pick only. Why 2? Because a veteran GM knows who to pick for their power picks and can get the jump on those new to the game. With 3 really good picks, they only need 1 good regular pick and they are pretty much guaranteed teams. Every draft someone gets more powerful. Trying to limit or get rid of them doesn't work because someone else comes along and gets more powerful. Xavier's stock rose because of his now as of yet undefined limit. Hourman's rose as well. In previous games it was Blink, X-Man and Strange. All it takes is a bit of research and these characters all seem a bit all powerful.