The official Pokemon movie site was updated last night and the latest preview, the latest poster, and information on the characters and story was announced.
During the preview, parts of the movie theme song "ONE" sung by Crystal Kay can be heard. Unlike last years song with Sarah Brightman and Chris Thompson, it seems this song will be completely in Japanese.
You can view the new trailer on the Offical Pokemon Movie 11 website.
Sources:
Crystal Kay Official Web Site and
Official Pokemon Movie Website