Unlockable characters
     Go  throughout  story mode (Another Road) to unlock the following
characters:

Bardock: Defeat him as Goku in Chapter 5
Dubora: To unlock Dubora, beat him in the second level in chapter 2
Future: Gohan Finish Chapter 5
Picolo (Fuse with Kami): Beat him at the alternate path of Chapter 3
Super Buu with Gohan absorbed: Finish the third level of Chapter 7
Super Buu with Gotenks absorbed: Finish the second level of Chapter 7

Be in Super Saiyan form when starting a battle!
     To  start  in  Super  Saiyan  form  when  you immediately start a
battle,  hold  [L]  when  choosing  your  character and press [X], and
you'll  hear  a  "cling"  sound, different from normally choosing your
character  with no [L] held down. Remember, for this to work, you have
to hold down [L] and press [X] on the Super Saiyan form when choosing,
not the normal one.