Dragon Majesty releases September 07, 2018; with Dragonite-GX.
Agreed, to an extent.
Remember, you'd only have up to 4 Giratina.
So, bench would likely be:
Giratina
Giratina
Giratina
Giratina/Back up Cofagrigus
Back up Cofagrigus
So, 120/150 damage, 30 from CB.
Next turn bring back 3...