The official Japanese Pokémon website announced a special live webcast that was streamed over U-Stream on September 4th, 2011. The broadcast featured the MTM band with Battle Woman M live. The event was called Pokémon Smash! Everyone Sing! Can You Say the Pokémon? BW in Roppongi Hills (「ポケモンスマッシュ！」みんなで歌おう！ポケモン言えるかな？BW in 六本木ヒルズ). The event took place at Roppongi Hills (六本木ヒルズ) which is part of Tokyo.

Misaki Momose, Shinji Miyazaki, Akihito Toda and Junichi Masuda were once again on hand to perform the song Battle Gene M (バトル遺伝子Ｍ) which is based of the Pocket Monsters Black and White background music track Battle! Shirona (戦闘！シロナ), track 50 on CD #3 of the soundtrack.


Click on images for higher resolution
The live broadcast and the rehearsal are available on the U-Stream archived video page at http://www.ustream.tv/user/Pokemon_USTREAM/videos.

Update: Junichi Madusa updated his English Director's blog on the GameFreak website to post a bit more information about the event. "Three songs were performed! Long ago, when “Pokémon Smash!!” was called “Pokémon Sunday”, Shokotan visited Game Freak for asking one song from me. Therefore, I created the song, and that song was performed by MTM! And next comes to… MTM with battle woman M’s theme of Cynthia. Lastly, Music of legendary Pokemon’s music with Victini.

Source: http://www.pokemon.co.jp/info/2011/08/110826_e01.html

Neat. It's probably a good idea, since Japanese attendance of Worlds was low.