I have a strategy to beat Pyroak with Stratagem on Sweatin'.
That by using Ancient Power Weak, so it goes fast. Then jump and do your strong air attack. Pyroak can do 5 things to stop Ancient Power, he can block, use Ember, use Energy Ball, use his strong attack, or jump. If he does any of these, usually your strong air attack will hit him. When you're in close do quick weak attack, alternating between low and medium. Usually it can keep him stopped so you can build up some more damage slowly, but watch out for when he comes back, if you're close he can Wood hammer twice.