While the official series ended its PSP run years ago, the modding community has kept the experience alive with "Version 9" and beyond. Key features include: Expanded Roster:

Dragon Ball Z Shin Budokai 9 : The Ultimate Fan-Made Mod for PPSSPP Dragon Ball Z: Shin Budokai 9

Many mods require specific save data to unlock all characters immediately. You can find these on community forums like Quick Game Overview