Successfully complete the indicated task in Planet Superstars mode to unlock 
the corresponding ball game:

Puyo Pop Fever: 
Successfully complete "Get A High Score!" in the "Puyo Puyo Fever" stage

Space Harrier -  
Successfully complete "Get A High Score!" in the "Space Harrier" stage

Virtua Squad - 
Successfully complete "Get A High Score!" in the "Virtua Squad" stage