I've seen people using a 3th generation Pokémon in B/W before they even finished it!
Is it possible to:
Import a Pokémon from my finished HG/Platinum game to B/W? If no, is it possible to import a Pokémon from someones finished B/W game to my B/W game via Wifi and friendcodes?
Thank you! :D
There's no limitation among trading National Dex Pokémon over to your B/W, even if you didn't beat the main story. You can't do anything like transfer your own Pokémon over until you did defeat the Elite Four, but at least you can trade with a friend that already did defeat the Elite Four and have access to 3rd Generation Pokémon.
However, you can transfer the Event Legendary Dogs and Celebii over using the Relocator. There's a clown in Castelia City inside an office where you'll be asked for a password. The two phrases are "EVERYBODY HAPPY" and "SIMPLE CONNECTION". You'll then be able to send over the Event Legendary Dogs and Celebii for the Zoroark/Zorua event.
Also, the Dream World is a perfect place to get National Dex Pokémon without needing to beat the main story.
EDIT: Hurrah! We broke 2000 posts in here.