Toho, the company that distributes the Theatrical Version of Pocket Monster has applied to Guinness Book of World Records for "The movie series with the most number of advance ticket sales in the world".

The last two Pocket Monsters movies have had at least 2 million pre-order ticket sales, mainly due to the fact that viewers get the ability to download a special Pokemon as part of the pre-order ticket sale.

Source: http://www.chunichi.co.jp