Donphan prime is pretty ok. Soon the format will change, so if he/she does put Donphan in the deck, it might not be there for long if they play by tournament rules. Now then, I have to say it might not be the greatest idea to put Gothitelle, Zekrom, AND Donphan Prime in the same deck. Donphan requires ALL Fighting Energy for his attacks, Zek needs two for one of his attacks. Assuming he/she is using the Magic Room Gothitelle, It might not be the best either since it's a stage 2, without any Psychic or Special energy, the pre-evolved forms will have no chance. I feel as if it'll be a little too much work to have Gothitelle and Donphan at the same time.