You'll probably want to take care of
the way to this trophy.
But if you want to grind this trophy as fast as possible (or finish it off after the above trophy) go into trials mode, any character you feel you can do a ultra move with and any trial. The trial mode will give you full "ultra" bar. Then just do your ultra move, wait the 3 seconds it takes to recharge (and for dan to reset) and do your ultra move again. It should take you less than an hour to bang this out, and far faster than grinding it out in versus mode.