Wii Friend Codes Not Universal » DigitalBattle:

It was revealed quite some time ago that the Nintendo Wii would support one universal friend code. This would mean that all you would need is one code, and that code would be used for every single game online. Pokemon Battle Revolution released in Japan last Thursday, as the first Wii game with online multiplayer enabled, and some disappointing news has surfaced. The game does not rely on the universal friend code from your Wii, but requires a new friend list which uses a different individual friend code format. If this is the case, then why was the Wii Friend Code system implemented in the first place? Just for Mii interactivity? This would mean that the Wii is following the same formula for the dreaded Nintendo DS Wi-Fi Connection system.