I think this the best deck for auto battle, at least is the one that has the best results with this event.
I have been running 9 accounts since MI for trades (this is way too many to feed one account), so far giratina beats 18 articuno and darkrai for win rate.
The AI really likes to waste energy retreating 1 retreat cost pokemon, so I recommend you run high retreat cost (2 or 3), 0 cost also work but there are few of them and I haven't tested them.