After successfully completing twelve grudge matches, a doppelganger of your character will appear in front of your team's clubhouse, looking almost exactly like your main character. You'll be forced to fight him. Defeat him to accomplish the following.

Defeating him the first time will net you the Majel Robo, the Indigo Gun, Indigo Bomb, Indigo Pod, and Indigo Legs, as well as a pass that will allow you to access the underground. After defeating the Greybaum enemies with the boss data, you can again fight the doppelganger. This time, he will give you the Ray II Dark Robo, Ripple Laser Gun, Deva Bomb, Cerberus Pod, and Phantom Legs.