I don't think Cross Chop is a replacement for Mach Punch. They are both fighting attacks, but one is used mainly for priority, while the other one is for breaking walls.@ Expert Belt with Cross Chop over Mach Punch if TTar or Blissey gives you trouble.
Same logic could be applied to Stone Edge.Cross chop's shitty accuracy and PP are enough to dissuade me from using it pretty much ever.