The Japanese Pocket Monsters movie site as well as the official Japanese Pokémon wesite have updated with most of the details of the upcoming Movie 16 pre-order ticket distribution. Mewtwo will be distributed to those that pre-order tickets from April 20th, 2013 until July 12th, 2013. The actual distribution will take place from June 20th, 2013 until September 1st, 2013.

The details of Mewtwo are as follows:

Pokémon Info
pic Level: 100
Poké ball: Cherish Ball
Ability: Unnerve
Held Item: Custap Berry
Attack 1: Psystrike
Attack 2: Ice Beam
Attack 3: Heal Pulse
Attack 4: Hurricane

Pre-Order Ticket Information

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Pre-order tickets can be purchased from: 7-11 (セブン-イレブン)、Ito-Yokado (イトーヨーカドー)、Aeon (イオン)、Toys"R"Us (トイザらス)Apita (アピタ)Piago (ピアゴ)Al-Plaza (アル・プラザ)Heiwado (平和堂)Daiei (ダイエー)、Fuji (フジ)、Pokémon Centers (ポケモンセンター) and various movie theater locations throughout Japan. General admission is 1300yen, youth admission is 800yen and a parent/child combo is 2000yen.

Sources: http://www.pokemon-movie.jp/tickets/ and http://www.pokemon.co.jp/ex/movie2013/