From what I have seen so far Valk out powers Hazama by a lot but Hazama can control the match better, The only real problem I seem to have while fighting a Valkenhayn is when he transforms into the wolf and charges at me. I have a hard time knocking him out of it.
Other then that he is easy to bait and long-mid is range and at close range he is pretty much at your mercy. Valk has some nice mid range stuff that can jack you up but if you get in close he seems to get beat out by a lot of Hazama's moves.