Pokémon Black and White/Pokémon Global Link

The Pokemon Global Link is where you can access the Dream World, change some Pokemon White/Black game settings, and access the Global Battle Union.

Dream World
When you have a Pokemon sleeping in a PGL-Synched game, you can access the Dream World.
 * See the Dream World page for more information.

Campaign
This option lets you obtain limited-time new Pokemon, C-Gear Skins, Pokedex Skins, and Musical songs.
 * All Campaigns are available for only a set time. After it's over, it can not be obtained, same as Mystery Gift Events.
 * Some Campaigns do re-occur, but this is rare, and has thus far only occurred for Japan.
 * Some Campaigns are password-locked, some are not. Some Passwords are constant, the same for everybody; Often these can be found on sites such as Serebii.net. However, others are one-time usage codes, usually a unique serial code given out with a Pokemon-related product.
 * Some Campaigns have other triggers to become available, such as an event in the Dream World.
 * Not ALL Skins/Songs are unlocked via Campaign. Most are though.

Customize (B/W Game Settings)
Once you've obtained a C-Gear Skin, Pokedex Skin, or Pokemon Musical song, it becomes available as a game setting here. To change it in your game, just select what you want the current setting to be, save the changes, and then either have a Pokemon dream or wake up to transfer that data to the game.
 * Note: Only one of each setting is stored on the game at a time, and can only be changed via this option on the PGL.

Global Battle Union
You can view your ranking in Random Match battles, among all gamers around the world. You can also see who the top ranked Trainers are.