When you are selecting the difficulty of the CPU change to level 9.
You can do this 2 ways, getting good or 'cheesing' the game.
If you are skillful enough you can get this by using your main character and defeating the CPU.
If you want to cheese this simply change the stock to 1 each (so if either you or CPU die then the match ends). I found that on some larger maps the CPU can jump and accidentally kill themselves, granting you the victory!