Instructions
Obtaining the Member's Card
Visit the official Pokemon website for news and updates about special promotional events to obtain Darkrai. They will advertise the Pokemon rather than the item received to access the Pokemon.
Visit a participating store during the days the event is active and connect to Mystery Gift and select the 'Get From Wireless' function on your DS.
The DS will pick up the wireless signal that is being sent by the event machine and a Wonder Card will be sent to you in-game.
Select the 'Flip the card' option for the Wonder Card. You will be asked to retrieve the gift (in this case the Member's Card) at a deliveryman in any PokeMart in-game.
How to Activate Mystery Gift
To activate the 'Mystery Gift' function for the Diamond, Pearl and Platinum versions of Pokemon, take your trainer to the Jubilife TV Center in Jubilife City.
Locate the man who accepts battle greetings from you on the 2nd Floor (Diamond/Pearl) or 3rd Floor(Platinum) of the TV Center.
Open his dialogue box and input "EVERYONE HAPPY" for the first greeting and then "WI-FI CONNECTION" as the second. Mystery Gift will be unlocked and accessible when you start the game on the main menu.