From Bulbanews, your community Pokémon newspaper.
Service expected to resume before BW2 release
The Pokémon Global Link will be unavailable until June 19, the Official Nintendo Magazine has reported.
The downtime is due to a period of scheduled maintenance, in which a new Dream World area will be made available. The area, Cold Hole, will be accessible starting June 23, which is the same day that Pokémon Black 2 and Pokémon White 2 are released in Japan.
While the service is unavailable, any tucked-in Pokémon cannot be woken up. Players are also unable to access the Dream World, use Game Sync, or use any other Pokémon Global Link features.