Start/End Dates	2011-12-15 through 2012-02-16
Country	United States

Details

Press Release

Befriend a cool Mamoswine at the Pokémon Global Link with this password!

It may be getting colder outside, but your Pokémon battles are about to heat up! Copy down the following password and enter it at the Pokémon Global Link to befriend Mamoswine, a huge Ice- and Ground-type Pokémon that's ready to send chills through your opponents. This Mamoswine has the Thick Fat Hidden Ability, a trait exclusive to Mamoswine found in the Pokémon Dream World. Thick Fat provides extra resistance to both Fire- and Ice-type attacks, making this already tough Pokémon even harder to defeat!

The password is: POKEMONDOTCOM

Once you befriend Mamoswine at the Pokémon Global Link, use Game Sync to add the cool Pokémon to your copy of Pokémon Black Version or Pokémon White Version. Don't wait—Mamoswine will be available for only a limited time!

Source: http://www.pokemon.com/us/news/vg_pgl_mamoswine-2011-12-14/