There is a couple of techniques I use. One way is to jip (jump in punch) and then uppercut. It hits him most of the time but not all. One of my favorite combos to use on him mid-screen is j.i.p., back+X, Y, freeze, Y, X, B, slide. Now if he gets in the corner, do this combo: Y, X, B, freeze, Y, X, B, slide. Sometimes the CPU blocks this combo from the beginning. However once you get stopped at the freeze part, just spam it and you'll win the round. But if you have X-Ray, instead of doing the slide at the end of the combo, use your X-ray for 50% damage. I learned these combos and more off a combo tutorial on Youtube. Oh and if you didn't know this if you finish a mid-screen combo with the Y, X, B, and you have X-ray, hold onto the X-ray for about half a second, or a whole second, and then release, you'll be able to hit them.