The ISO supports Ad-Hoc multiplayer, which was the gold standard for local play back then. Gathering friends in a cafeteria with PSPs to play PES 6 was a massive social phenomenon in schools and universities. The framerate and gameplay mechanics were tuned perfectly to handle the wireless connection without lagging.
These packs replace the old 2006 menus and stadium turf with modern, high-definition assets. How to install them on PPSSPP:
Navigate to the "Games" tab and browse to the folder where you saved the ISO. Click on the PES 6 icon to start the game. Best PPSSPP Settings for PES 6