Access to:
Southern exit: Route 15
The Poké Transfer Lab is used to transfer Pokémon from Diamond, Pearl, Platinum, HeartGold, or SoulSilver into Black, White, Black 2, or White 2, using a second DS and connecting using the DS' Download Play feature. After transferring up to six Pokémon, the player can catch them in the Poké Transfer Lab in a minigame. For a detailed explanation of how certain aspects of a Pokémon's data structure are handled during the transfer, see Bulbapedia's page.
The catching minigame has a time limit. If any Pokémon is not caught in the time limit, it is returned to the game from which it came. Otherwise, if a Pokémon is successfully caught during the minigame, it can never be transferred back to Diamond, Pearl, Platinum, HeartGold, or SoulSilver.
Pokémon can only be transferred if the copy of Diamond, Pearl, Platinum HeartGold, or SoulSIlver they are coming from has the same language as the copy of Black, White, Black 2, or White 2 they are transferring to. Pokémon that know HM moves cannot be transferred.
The shiny Legendary Beasts and the special movie event Celebi that were distributed for Diamond, Pearl, Platinum, HeartGold, and SoulSilver will not activate their events in Black and White if they are sent through the Poké Transfer Lab. Instead, they must be sent with the Relocator feature, or sent to Black 2 or White 2 and then traded to Black or White.