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Sanrio Smash Ball
Goal: Beat Court 15
Select Keroppi on GO
.done on your 3rd goal on Court 15

Y - Left Kick
B - Right Kick
X - Power Kick

Your goal is to score into your opponent's goal, best 3 of 5. Losing around lets you continue infinitely.
You can charge up a power kick by holding either kick while standing still, and can use your power kick when the meter is full.
The bonus games let you get a small upgrade if you get enough points, but aren't a big deal. You can fail on purpose or go for the speed/power upgrade (will be a little slower playing it out, but you can't skip it either).