Obviously, set the rounds to one and timer to 30. I didn't have a single round time out doing it this way, though.
Pick Sektor. On almost every character this works flawlessly once you get a rhythm. Jump backward and do the teleport uppercut. 75% of the time, they try to throw a projectile to catch you on the fall. If you're fast enough, you'll go through the ground and hit them. then, do the away +2, then 1 attack combo. It does 19% damage. Immediately jump back and repeat over an over. Learn the timing and you dominate. It works on Shao Kahn as well, so the intimidation factor is voided. Just be careful on Kintaro/Goro. Do not jump back and do it so fast. Wait for them to open themselves up and them do it, or lead in with a jumpkick and then do the teleport combo.
I tried Sheeva and never could make it past match 5 or 6. Sektor flat out dominates!