C-Gear is a new system that can be used to access wireless, Wi-Fi, and infrared multiplayer options.
C-Gear can be used to quickly warp to the Entralink forest, a location in cnetral Unova. Here you can gain Pokemon from Nintendo's official Pokemon Dream World with Dream Balls. You can also use Entralink to warp to other player's Unova and undertake various missions. These multiplayer missions reward Pass Orbs that can be used to gain exclusive Pass Powers that aid all nearby players.
Xtransceiver can be used to directly communicate with players via the DS' mic. If other players are also using the DSi, video phone communication can be achieved with the built in camera.
Global Link can be accessed early in the game by entering the Dreamyard and collecting Dream Mist from a Munna. If you bring this item to Fennel in Striaton City she will unlock this new Wi-Fi mode.
You will need a Nintendo Pokemon Global Link account to access the Dream World itself. Due to server traffic, there are limits on time spent in Dream World. Most often you will only have one hour of access a day to this feature.
Dreamworld can be used to gain extra Pokemon, find items, and explore Dream Island. In Dream World you are also given a home which you can furnish and redesign. You can also trade and take items via the Share Shelves in your home.