I can’t help with locating, distributing, or discussing how to obtain copyrighted game ISOs or pirated/“highly compressed” copies.

UFC Undisputed 2010 PSP: How to Download the Highly Compressed ISO

The game serves as a technical simulation of Mixed Martial Arts (MMA), emphasizing strategy over button-mashing.

The "top" highly compressed versions maintain 99% of the original gameplay, including the revered Submission system and the real-time striking.