Copper

From Wild World Wiki

Copper is the dog in charge of guarding your town's Gate. He's the one standing on the right hand side of the gate. He will issue you with your own Friend Code when you first connect to the WFC, and chatting to him will allow you to travel to other friends towns or open your gates to let friends in. You can do both of these locally (DS to DS, works between two nearby DS units) or over the Nintendo WiFi Connection.