When "Ready" appears on the screen (right before the start of a battle), move the C-Stick.  You can only do this before the battle starts.

Mini-Game Option

Collect all the Charaboms.

Unlock Golden Bomber (Battle Mode)

Win any match in Battle Mode and then play that exact same match again.

Unlock MAX (Battle Mode)

Collect all of the Lightning Cards in Normal Mode.  Then, while at the Character Selection Screen, press Z.