First of all you need the "Liberty Pass" witch you can get on Mystery Gift.But the special oppertunity in now over because you could have got on board December 3-December 31 but the oppurtunity is now sadly over.Though they may have something for Pokemon Black and White 2 witch comes out Fall 2012!!
get the national dex and wait till the evening to board
In the royal unova
The Unova Region. It is very, very far Region.
Shuckle is the #232 Pokémon in the new Unova Regional Déx, from Pokémon Black and White 2.
You have to use the Unova Link, and you can use the Infrared connection with someone who has Pokemon Black 2 (which has Black City), and receive the key from them.
get the national dex and wait till the evening to board
the evening
In the royal unova
Yes, you can take the Royal Unova Challenge again.
The Royal Unova resides in Castelia City in Pokémon Black 2. Unlike Pokémon Black and Pokémon White, the Royal Unova can be boarded at any point in game play in Pokémon Black 2 and Pokémon White 2 as long as it's boarding time.
The Unova Region
a region known from pokemon black and white.
There are 300 Pokemon in the Pokemon Black 2 and White 2 Unova Pokedex.
The Unova Region. It is very, very far Region.
The Royal Unova will leave as soon as you get on it. You must show up between 5pm and 8pm or it will leave without you at 8pm.
You can't. Unova is the only region for Black and White.
Unova is the only region you can play through in Black and White.