Virtual Smash has you punching or kicking blocks as fast as you can to amass points as quickly as possilble and is found in the Gym Games menu. Set the difficulty to easy and start the mini game. You need to make sure you punch across your body or the hit will NOT register. On easy you will only use punches and the pattern is the same each round:
Left, right, left, right, left, right, left, right, middle. Repeat.
As soon as you see the left square turn green punch it and start the above combo. Don't bother punching high or low, just punch between the upper and lower boxes and you will register the hit regardless of where the box actually is. Then it is a matter of just counting to 8 with the ninth punch being in the middle. You will easily reach over 1000 points if you just keep punching left to right.