2nd characters: Every character has an alternate so if you fight the same character you know which one is yours. Here is how to access the 2nd character for each person. When selecting your character simply press "L1" and hold. You will notice the face of your character change. While holding "L1" simply pick that character. For example, Leia is normally in her Boush outfit with out her bounty hunter mask on, If you press "L1" and select her, when the fight begins she will be wearing her mask.
Level select: To pick which level you fight on simply beat the game on Jedi with Chewbacca.
Big Heads Mode: After selecting your fighter simply hold select down until the amtch begins.