For those interested in deeper modding beyond the save file, the UFC Undisputed community has documented the various file types used in the game, such as .PAC (containers for fighters and objects), .TEX (texture files), and .DDS (Direct Draw Surface textures editable in Photoshop or GIMP).
Repacks typically focus on transforming the base 2010 game into a "UFC 5" or "UFC 2026" experience. ufc undisputed psp savedata repack