Dragon Arena: If you have unlocked everyone, then simply beat Dragon Universe with every character (10) EXCEPT Broly (who makes it a total of 11 characters). If you have already beaten roly's Dragon Universe,
and still don't have Dragon Arena,...you must beat it, AGAIN, with everybody EXCEPT Broly.
In order to enter a password into Dragon Arena, press R1/R2 (it's one or the other) when the "choose you opponent" screen comes up. If you never entered a password before, this screen should be blank. Now press either start or select to begin the process of entering a password.
Death is but a door, Time is just a window,...I'll be Back!!!!!