The official Pokémon movie website has updated. Translations follow:

We Get a Concentration of Super Extravagant Guest Voice Actors in "Pocket Monsters the Movie: Everyone's Story"

We will now announce the "everyone" that will be a part of
"Pocket Monsters the Movie: Everyone's Story", which premieres Friday July 13th, as guest voice actors.

In the role of Largo, the mysterious little girl that hangs around in the forest all by herself:
Mana Ashida, who keeps getting more and more range as an actress now that she's become a middle schooler.



In the role of Lisa, the highschooler and Pokémon rookie:
Rina Kawaei, who keeps getting cast in one popular movie after another.



In the role of Trito, the timid researcher that lacks confidence:
Gaku Hamada, whose reliable acting prowess makes him in high demand for both movies and TV serials.



In the role of Kagachi, the braggart that just can't stop telling tall tales:
Koji Ohkura, who always leaves a great impact on the movies he appears in.



In the role of Hisui, the old eccentric that hates Pokémon:
Masako Nozawa, a legend in the voice acting industry.



In the role of Riku, Pokémon fan and Lisa's younger brother:
Shoko Nakagawa, getting a role for the 12th year in a row.



In the role of Mayor Oliver, Largo's father and the face of Fura City:
Koichi Yamadera, getting a role for the 21st year in a row.



This year we got a concentration of "everyone" in the Pokémon movie, of all ages and genders.
Look forward to a Pokémon movie for all generations!!

For more information on the characters, as well as comments from the guest voice actors,
go here!

Source: http://www.pokemon-movie.jp/news/?p=3223