The official Pokémon movie website has updated. Translations of the new entry follows:

Win the world's only copy of the "Supported Pokémon T-shirt"! The "I Choose You! Backing Campaign for Your Supported Pokémon" is Underways!

The "I Choose You! Backing Campaign for Your Supported Pokémon" is currently be held at participating stores located all across Japan in conjunction with the "Pokémon Elections 720"!
The campaign will run until Sunday May 8th!

Win prizes featuring your personally "Supported Pokémon", which you can choose from the Pokémon with national zukan number 001-720, the sole exceptions being Volcanion and Magearna! This is your chance to get your personally "Supported Pokémon" as a prize, no matter if it gets merchandise often or not!

Purchase campaign products for 800 yen or more (including tax) and get a "Personal Entry Postcard"! Attach a 52 yen stamp to the postcard, fill it out with the Zukan number of the Pokémon you're supporting, as well as other required information, then send it in to get a chance to win extravagant merchandise featuring your personally "Supported Pokémon", including a "World's Only Supported Pokemon T-shirt"! Incredibly, there'll only be one t-shirt made for each of the 720 Pokémon, making each one the only copy in the entire world!
*Note that there is a limited number of the "Personal Entry Postcard" and that a store's distribution will end once they run out.



Extravagant prizes for a total of 1000 winners!

*The World's Only Supported Pokemon T-shirt
(one for each of the 720 Pokémon)
*The product image is of a product still in development.
*The product image is a single examples. The product varies depending on your "Support Pokémon".
*The Pokémon you can choose between when entering the lottery are all 720 Pokémon excluding Volcanion and Magearna.
*You can not choose the "Supported Pokémon"'s form (mega evolution, gender, etc).

*1 copy of a card featuring your Supported Pokémon & 1 Premium Champion Pack "EX+M+BREAK" box
(for 200 winners total)

*A Your Supported Pokémon MonCollé figure, gold metallic version
(for 80 winners total)
*This is for MonCollé announced after October 12th 2013, if the Pokémon you chose as your "Supported Pokémon" has not been released until April 16th 2016, you are not eligible for the lottery for this prize.

(1) Participating stores:
Apita/Piago, Aeon/Aeon Super Center/Aeon Style/Aeon Retail Store, Ito-Yokado, Toys 'R' Us, Fuji, Heiwado, Pokémon Center/Pokémon Store
*Some stores exempt
A full list of stores can be found here (opens a PDF file)

(2) Campaign period )currently ongoing):
"Personal Entry Postcard" Distribution period: Saturday April 16th to Sunday May 8th, 2016 *while supplies last
Application period: Saturday April 16th to Tuesday May 31st, 2016 *going by postdate

(3) Campaign products:

*this image is an example of valid products.
*valid products may vary between stores.
*some stores may not carry all the abovementioned example products.

*The Special Pre-order Ticket w/ Volcanion Present Code
*All Pokémon Card Game expansion packs, Pre-built decks, and similar items
*All Nintendo 3DS/Wii U Pokémon series video games
*All Takara Tomy Monster Collection (MonCollé) products
*All Takara Tomy Pokémon toys

For further information on the "Supported Pokémon campaign", go here

For further information on the "Pokémon Elections 720", go here

Sources: http://www.pokemon-movie.jp/news/?p=2057