There are probably many ways to do this, but I found a fast way to do it. Set maps to random to save some time. Go to Special Brawl and select Fast speed. Set the damage ratio at 9. Set the handicap of your enemy to 300%. Select Pit and an enemy. When the battle starts, press B. You should be able to KO the enemy with a single attack, ending the match in a few seconds. Press start to start a new fight. Rinse and repeat. Be sure to select a heavy enemy so that he's easy to hit. On some levels, you'll be forced to move to hit the enemy. Also, be sure to set the difficulty level of the enemy to a low one. You could also probably play against a human if you want.