The official Pokemon Movie website has released yet another trailer, elaborating that Kyurem's new forms do indeed originate from the power of Zekrom and Reshiram, as well as revealing that Keldeo appears to be frozen in ice prior to awakening in the movie, suggesting its injury was due to a past encounter with Kyurem. The trailer may be viewed below, with English subtitles:

Okay, so now we know what the Meloetta was doing at the bottom of the poster. One of my guesses for the plot is Kyremu is getting revenge on the humans, and the Fighting Trio don't want it to happen, so they help protect the humans.
Also, Kyremu runs like a chicken. I mean seriously!

kyurem can talk and arent the fighting trio supposed to not like humans?

oo i do like wat i see about thsi movie. i relly like zekrom so maby the zekrom kuyrem will be nice...

so its coming this summer for japan. heck we might not get an english event from this till maybe next year.