I haven't seen the Movie in awhile, but I recorded it (along with Movies 10c & 11) during the Pokemon Marathon the day Season 13 aired in US.
Anyway, this movie was great, probably the best out of the current 12. I thought Arceus's voice was kind of weird and he sounded better before he was in rage. Having the three Johto Starters air was great because this was before HGSS came out in the US so it was great to promote the games. The beginning battle between Ash, Dawn, & the twins (assuming they are twins) was great, and so was the extended version of Season 12's Theme Song.
The battle between Arceus against Dialga, Palkia, and Giratina was quite funny how Arceus made those three seem like Bidoofs! In their respective movies, they were the cream of the crop, and this just proves Arceus is the god of all Pokemon. The silver water almost killed Arceus, though.
Funny that TR was in the same room that Pikachu, Piplup, the three Johto Starters, and the Notched Eared Pichu (a nice addition, by the way), although Pikachu and Co. were in the past!
Overall, a great movie.