"Giratina and the Sky Bouquet" is a possible title for the 11th Movie and it is known to contain 5 pokemon: Giratina, Regigigas, Dialga, Palkia and possibly Shaymin.
Dialga and Palkia are shown again because the fight over who is the 'god' pokemon isn't over.
The rumor there is a undiscovered new 5th generation pokemon in this movie may be false because there are so many pokemon staring in it already and sinnoh saga is moving slower then hoenn. Thus why the first 4th gen pokemon Munchlax was revealed May 2004 before the 7th movie (second advance series movie).
Dialga and Palkia are shown again because the fight over who is the 'god' pokemon isn't over.
The rumor there is a undiscovered new 5th generation pokemon in this movie may be false because there are so many pokemon staring in it already and sinnoh saga is moving slower then hoenn. Thus why the first 4th gen pokemon Munchlax was revealed May 2004 before the 7th movie (second advance series movie).