A friend code is a code that is unique to every player, and is generated when you play Super Smash Bros. Brawl for the first time over Wi-Fi. Your friend must give it to you before you can play with him/her over Nintendo Wi-Fi Connection. The format is three sets of four-digit numbers, such as 0000-0000-0000. You can check your own friend code and add others on the Friend Roster. The system used in Brawl is the same for any other Wi-Fi title on a Nintendo system, both players cannot view each other's online status until they have both registered each other's Brawl codes, and even then they must have each other's Wii friend codes, too. Whilst friend codes are very personal and have the highest level of security to avoid unwanted "friends" from contacting you, they have proven to be quite a hassle. You can have up to 64 friend codes on your roster. After registering a code, you can play with the other player in a few different modes, including a regular online Brawl (with custom taunts usable), a Multi-Man Mode match with the other player as a teammate, a Home-run Contest, or even an up to 64-player Tournament Mode.
This function is now discontinued.