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

How to unlock "Bonus" section
     Beat  arcade  mode  once  with anybody and then go to the options
menu  and  select  bonus, and you can listen to in-game music and play
"dragon click"

Unlockable characters

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

Unlockable                        How to Unlock
Bardock                           Defeat him as Goku in Chapter 5
Future Gohan                      Finish Chapter 5
Super Buu with Gotenks absorbed   Finish the second level of Chapter 7
Super Buu with Gohan absorbed     Finish the third level of Chapter 7
Picolo (Fuse with Kami)           Beat him at the alternate path of Chapter 3.
Dabura 	                          To unlock Dabura, beat him in the second 
                                  level in chapter 2.
Vegeta (Majin)                    Get Ending A (Can be obtained by not 
                                  letting enemies destroy any city 
                                  in the last chapter)
Goku (SSJ4)                       Get Ending B (Can be obtained by letting 
                                  enemies destroy 1-3 cities 
                                  in the last chapter)