The official Japanese Movie website has updated with information on the annual movie drawing contest. Translations follow:

Organized by 12 Shogakukan magazines! The Pocket Monsters the Movie: Everyone's Story! "Created by 10000 People! Your Partner Pokémon" Drawing Contest

Using "The Your Partner Pokémon Drawing Contest: The adventure won't start unless ____ is there." as your theme,
draw your favorite Pokémon on the drawing form and send it in!
The winners from each magazine will have their name and drawing showcased in the movie itself!



And not only that: This year we'll pick 10000 people from the contest entrants and use their entries to create a gigantic piece of mosaic art featuring their Pokémon!

The Grand Prize (1 winner from each magazine, for a total of 12 winners)


*A New Nintendo 2DS LL Monster Ball Edition + one 3DS "Pokémon" game of your choice
Prize provided by: Pokémon
*Your drawing and your name will be presented in the movie and will appear in the mosaic art!

The Runner-Up Prize (5 winners from each magazine, for a total of 60 winners)


*A special movie MonCollé set
This is a special MonCollé set that consists of four Pokémon that play a role in the movie, one of them being Lugia!
Prize provided by: Takara Tomy
*Your drawing will appear in the mosaic art!

We will also create a gigantic piece of mosaic art from the drawings of 10000 contest entrants, which will be displayed at Pokémon Centers and events all across Japan.
List of exhibition areas (currently planned): The Next generation World Hobby Fair '18 Summer venues, Pokémon Centers, and more.

Submission rules (read through these with an adult):
Cut out the application form from one of these magazines or download one and print it out, fill in all necessary fields, then send it in.
Fill in the required information (postal code, address, child's name, phone number, gender, grade, name of other person in the household) on the application form for the magazine you wish to enter through,
then send it in on a postcard or standardized postcard. If you're not using a standardized postcard, don't forget to add a 62 yen stamp.

The submissions must have arrived by Saturday April 14th

Pokémon Fan issue 57, on sale February 28th
Kindergartener April issue, on sale March 1st
TV-kun April issue, on sale March 1st
First Grader April issue, on sale March 1st
Pucchigumi April issue, on sale March 1st
Ciao April issue, on sale March 3rd
Corocoro Comic April issue, on sale March 15th
Shonen Sunday issue 17/2017, on sale March 20th
Corocoro Ichiban April issue, on sale March 1st
Corocoro Aniki Spring 2018 issue, on sale March 15th


You can also apply via the "Shogakukan Child Education Division Web Site" and "Sunday Web Every"!
If you use the "Shogakukan Child Education Division Web Site" or "Sunday Web Every", you'll draw completely freeform without a printout and can submit your drawing via the Internet!
The "Shogakukan Child Education Division Web Site" starts taking such entries March 1st!! A link will be provided!
The "Sunday Web Every" starts taking such entries March 15th!! A link will be provided!

*All rights relating to the winning drawings (including the rights provided in Article 27 and Article 28 of the Copyright Law) shall belong to The Pokémon Company. 
Winners will not exercise any moral rights to winning drawings.
*Please note that submitted drawings can not be returned.
*Please go here for information on the handling of personal information sent with the drawings.

Announcement of winners:
Winners of the grand prizes will be announced in the movie itself alongside the winnners' names and drawings. All winners will be announced in each magazine's July issue (estimated to be on sale in June) and on the official movie website.
The 10000 picks for the mosaic art will be announced on the official movie website only.

Jury:
Tsunekazu Ishihara, Tetsuo Yajima, Ken Sugimori, Masakazu Kubo, Junya Okamoto, Hidenaga Katakami, Toho's advertising managers, each magazine's editor-in-chiefs (listed in no particular order)

Source: http://www.pokemon-movie.jp/illust_contest/