To choose three different Robopon at the beginning of the game you first have to get the Secret Cave Key from Nick and the Ion Battery from the dog in one of the houses. Then, go to the back of the house where you started from. Move left until you see a door. It will now open. Go in to get two batteries. The first can be found by going up and to the right, then down to find the Moon Battery. The other one is hidden. When you enter, go straight up and it will be a dead end. Move across the right wall and you will walk through it. It may take awhile to find the entrance. When you go through the passage, you will find a chest with the Sun Battery. You can now spark the Sun and Moon Battery to get Hexbot, Spark Ion, and Moon Batteries to get Sun-Zero, or Spark Sun and Ion to get Scooter.
This Robopon packs a powerful punch. He is a legendary little warrior who is almost as strong as SunZero. To get him, spark a Cyber Battery and an Ultra Battery.
Unlock Playland then talk to a fat man behind the training spot there. Then, go to were Ms. Rocket is and pay him lots of money that so he can build a spaceship. Note: It takes about ten times to make the ship Fly.
Unlock the Marvel lab and train there.