Here's what I did:
1) Make sure Fighter 1 has a higher Tiebreaker stat than Fighter 2.
**Try to scan something like the edge of a pillow, this shape always gave me the best fighter build**
2) Make sure both Fighters are similar in damage and health (This matters slightly less than Tiebreaker)
3) Keep doing the same move; you have a 2/3 shot at doing damage to your opponent so probability suggests you will win.
4) Select Rematch after your win and repeat until the achievement pops!
Note: You do not have to win 4 matches in a row; as a matter of fact, you can reselect your fight later and add to their win total.
Good luck!!