Instructions
Travel to any Pokemon Center in any city. The Pokemon Center is easily identified as the only building with a bright red roof and a Pokeball on it.
Enter the Pokemon Center and walk up the stairs to the second floor.
Speak to the woman behind the middle counter.
Select "Go to Wi-Fi Club." You will be connected with your friends and placed in the Wi-Fi Club.
Press "A" next to your friend's character.
Select "Voice Chat" for voice only chat or "Xtransceiver" for video and voice chat. You may connect with three players total in this way. Your friends are displayed in real-time on the top screen of your Nintendo DS.