My rough translation of the plot:
The story takes place a few years after the battle against Majin Buu. Birusu, a god of destruction who maintains the entire universe's balance, now has been awaken from his long sleep! He comes for Goku after hearing the rumor about a Saiyan who defeated Freeza, and against Kaio's advice, Goku challenges him, but he can't do anything against Birusu's massive power. "There must be a tougher guy on the earth", says Birusu, and then he leaves the place. Can Goku and his friends stop the god?!
It also says that characters who'll bring back your memories will too appear in the film, which obviously implies Pilaf and his gang.