Junichi Masuda appeared on
Pokémon Smash 50 to announce further details about the Mewtwo event revealed by Shoko-tan on
Pokémon Smash 49. The event distribution will take place from
September 26th, 2011 until October 31st, 2011 on the Japanese Nintendo Wi-Fi Connection for players of the Japanese versions of Pocket Monsters Black & White. This Mewtwo has PokéSma! (ポケスマ!) as its OT, has the Pressure Ability, has a Premier Ribbon, comes in a Premier Ball, is holding the King's Rock item and knows the moves
Psystrike,
Shadow Ball and
Aura Sphere. Mewtwo has a fourth move but it won't be announced until
episode #51 of Pokémon Smash, which airs September 25th, 2011.
Source:
http://www.pokemon.co.jp/ex/mewtwo/feature/index.html#feat01