The official Japanese Pokemon Twitter has revealed Xerneas from Blue Impact. Thanks goes to Ryah R. for the translation!
Xerneas – Fairy – HP120
[Y][C][C] Rainbow Force: 10+ damage. This attack does 30 more damage for each type of your Benched Pokemon.
[Y][Y][C][C] Power Creation: 80+ damage. If this Pokemon recovered any HP during your turn, this attack does 80 more damage.
Weakness: Metal (x2)
Resistance: Darkness (-20)