For 2U, pretty much everything comes up in one form or another because the HSC is essentially the same, just a little more difficult, and a few extra topics. So all your differentiation, trig, quadratics, etc.
For 3U, parametrics always comes up, so does all your double angle and t formulas, circle geometry, polynomials, perms/combs, angle between two lines, ratios...ok so pretty much everything so just study everything because there is always a chance it will come up.