The PSP is one of the greatest emulation devices ever made. With custom firmware, your PSP can emulate the NES, SNES, Game Boy, Game Boy Advance, and even the Nintendo 64 (with varying success). This means you don't need a "Super Mario PSP ISO." You need an and ROMs (the game cartridge dumps).
While some "Mario Collections" are shared as ISO files, these are usually just custom discs that bundle an emulator and ROMs together into a single bootable package. If you find one:
Software that mimics older consoles (NES, SNES, N64) to run original Mario ROMs.
: This is a direct port of the N64 classic that runs at a full widescreen 16:9 aspect ratio, offering a better visual experience than many official versions. PSP Mario: The New Worlds : A high-quality clone of the original NES Super Mario Bros.
An ISO file, also known as an ISO image, is a type of file that contains the exact contents of a CD, DVD, or other optical disc. It's essentially a digital copy of the physical disc, including the file system, directory structure, and data. In the context of gaming, ISO files are often used to distribute games, especially for consoles that are no longer supported or have limited game libraries.
This is arguably the best way to experience Mario on a PSP. Developers successfully reverse-engineered Super Mario 64 to run natively on the PSP hardware. What it is