For those who want immediate access to the 24-character roster (plus transformations), the PPSSPP emulator allows you to import external save data.
: Go to the folder where your PPSSPP is installed, then navigate to Paste the Folder : Drop the extracted folder directly into the Boot the Game Shin Budokai 2
(Super Saiyan 4) : Achieve a or higher in the fight against Kid Buu in Chapter 7.