Donphan with Dragons is definitely the strongest variant. I preformed fairly well with it at Nats, and every game I lost was down to like the last prize. My list ran 2 Zekrom and 2 Reshiram, and it seems as if the average energy lines are 6 Fighting and 3 DCE. Also stupid DD and it not being rogue anymore, now people will be expecting to see it at the Worlds grinder. I'm pretty upset because I thought I was the only one who had thought of the combo, but then there were like 20 other people with it at Nats. Any other tip of advice I can give you is if you have a set of Victory Medals, play them.