The official movie website has updated with details on the movie. Translations follow:

Atsuto "Ucchy" Uchida of the national Japanese Soccer team will try his hand at voice acting for the first time in the Pokémon movie! His character's name is "Uschi"!



Atsuto Uchida of the national Japanese soccer team is going to be a guest voice actor!! This is the first time ever an athlete gets a role in a Pokémon movie.

From his early childhood, Uchida constantly played soccer when he was outside, but when he played indoors, he almost exclusively played Pokémon games. Now, he gets to try voice acting in this franchise he's know since he was a child as his first ever attempt at dubbing. The character he plays is one of Satoshi and Pikachu's co-stars, a hotel porter who looks exactly like Uchida! The character is named "Uschi", after the nickname Uchida has been given in Germany, where he currently plays. Look forward to the scene in which he appears!



A personal comment from Atsuto Uchida:
I rarely get all that emotional when I speak since I'm not very good at expressing my feelings with words, so emoting (when voice acting) was hard for me. I've played the Pokémon games with my friends since I was in grade school, so I was extremely happy when I was asked to voice act in the movie, though. Even children who don't know who the soccer player Atsuto Uchida is will now get to remember me as "Uschi". Please look forward to the scene I appear in!

Source: http://www.pokemon-movie.jp/news/?p=1261