The most common way to "mod" the game. These codes allow for infinite stamina, one-punch KOs, or playing as unplayable bosses. Texture Packs (PPSSPP): If you are playing on a PC or mobile via the PPSSPP emulator
Visual customization is huge in the modding community. Modders can replace the texture files (often in .png or .dds format) within the game’s ISO. fight+night+round+3+psp+mod
The PSP modding scene lives primarily on niche forums and social media groups. If you are looking to download mods, check out: The most common way to "mod" the game