Independent coders have occasionally designed small-scale homebrew soccer mini-games themed around the anime, compiled into an execution format that can be read by a PSP as an ISO or EBOOT file.
When you see a "Game Inazuma Eleven Psp Iso" available on the internet, it generally falls into one of three categories: Game Inazuma Eleven Psp Iso
Most fan-made PSP ISOs come pre-packaged with QoL patches: Game Inazuma Eleven Psp Iso
If you have acquired the ISO file for personal archival, here is the typical setup for running it: Game Inazuma Eleven Psp Iso
To play the game, you need the game disc compressed into an .iso format.