I have the cube version. From what I have read, all three exclusive characters are somewhat overpowered in their own ways. I use Link a lot in 1p mode because he is way better than anyone else at chucking people out of the ring.
Guardimpact.com put up
this chart, but that's all relative.
I would say I am probably best w/ Seung Mina and worst against Cassandra right now.