Pokémon Black & White (be warned: spoilers)

[Rosencrantz]

The first WiFi Event in Pokémon Black & White gives you the special item, the Liberty Ticket. This ticket will give you access to a special area in Isshu where you will find the Pokémon Victini in the wild. This allows you to capture Victini and is the only way to obtain it.

not sure if this is just how they worded it or not

but it sounds like you can get a lot of these things