3-1-2 Emboar (Ability)
Pokemon Total = 26
3 Rare Candy
2 Junk Arm
3 Proffesor Oak
Trainer/Supporter Total = 16
Energy total = 15
While Donphan prime is a powerful, fast attacker, I dont think it flows well with the other pokemon of this deck. I think it would be better to focus on the other lines and drop the donphan completely. Cincinno is definitely an unexpected tech in a deck that looks a lot like a magneboar deck, so I'd like to keep that in. I'd add in another magnemite and tepig in case you lose one early due to pokemon catcher. Otherwise I think your lines of pokemon are really strong. If you have one more ability emboar, it would be ideal to add it to increase the chance of you getting one set up as early as possible. Or you could add in the other emboar as an alternate attacker.
By dropping the donphan, you can drop the fighting energy as well. I'd use those extra spaces for fire energy. I might even consider taking out the DCE and replacing them with fire energy as well since emboar will let you attach them all at once. You won't need them for reshiram and cincinno as long as you have emboar in play.
You need to be able to search out basics early with 4 pokemon collector. I'd increase your fisherman to around 3 and also add in a few energy retrieval to ensure that you can get the energy back from the discard pile for emboar. I like cheren as a draw supporter, but 3 will be much more helpful. Since you have twp stage 2's, maxing out your rare candy and junk arms at 4 each will ensure that you can get them up as fast as possible. It's likely that you'll still be behind at the beginning of the game, so adding twins will help you get back. You also have pokemon with heavy retreat costs, so I'd add in 2 switch as well.
By removing the donphan, you should have more room for trainers/supporters that will make this deck faster and more consistent. Since you rely on two stage 2 lines, you'll need as much speed and consistency as possible for a few wins! Good luck!