The 2013 International Challenge will take place from January 25th, 2013 at 00:00 until January 28th, 2013 at 23:59 and it is the first International Wi-Fi tournament for Black 2 and White 2 that is open to all regions to participate against each other. There was three entry categories: Junior (born after 2002), Senior (born between 1998 and 2001) and Master (born before 1997). Players that participate in the competition will receive a Jaboca Berry as an entry gift.

The following Pokémon are banned from the competition: Mewtwo, Mew, Lugia, Ho-Oh, Chatot, Celebi, Kyogre, Groudon, Rayquaza, Jirachi, Deoxys, Dialga, Palkia, Giratina, Phione, Manaphy, Darkrai, Shaymin, Arceus, Victini, Reshiram, Zekrom, Kyurem, Keldeo, Meloetta and Genesect.

We have added a Wi-Fi competitions page that lists the details of all the Wi-Fi Competitions that have taken place for Black 2 and White 2. It will be updated as new tournaments are announced.

Source: http://ja.pokemon-gl.com/about/sp/ic2013_01/