Technically, an official Budokai Tenkaichi 3 for PSP does not exist. When you search for a "highly portable" or "highly compressed" PPSSPP ISO, you are typically finding one of two things:
Features updated HD textures, revamped menus, and new aura effects designed to match the "Tenkaichi vibe" . dragon ball z budokai tenkaichi 3 iso ppsspp highly portable
Available on the Google Play Store, App Store, or the official website. Technically, an official Budokai Tenkaichi 3 for PSP
But for modern fans, the question is no longer "How do I play it on a PS2?" It is: dragon ball z budokai tenkaichi 3 iso ppsspp highly portable
Dragon Ball Z: Budokai Tenkaichi 3 was never officially released for the PSP, a popular "Highly Portable" version exists as a massive community mod for Dragon Ball Z: Tenkaichi Tag Team