I'm trying it out right now. It works fine, except for the fact that you need to stand still to punch someone. Walking while in the middle of an attack will also cancel it.
Attacking while running no longer makes Jimmy tackle, instead it gives him the normal running punch thing that most students use. The attack can be spammed however, and if you do it while being grappled you will instantly get out of the grapple.
I managed to lose by going out of bounds when Russell tackled me onto the stages. I ended up on the infirmary, and I still had the weird fight style.
Other than that, good job. I had a fun time playing it.