^ No. No. Awful, Terrible. 60 for one is pretty good (avg), 120 for one is amazing (weakness), but 40 for one (most basics with Eviolite, Tornadus, Yanmega) is bad and 20 for one (Tornadus with Eviolite) is abysmal. Pair this with the fact that Thundurus and Tornadus can realistically swing for 80 (and Yanmega for 70 for that matter) by turn two, and you have a fairly meh attacker with good defense due to Exoskeleton. In the NV format however, Donphan has no good answer to Reshiram and is a borderline scoop against Tornadus. Straight Donphan is a terrible idea and will not work, and even if it still did, 14 energy is excessive for Donphan alone since it can attack for one. Having no draw supporters, quite frankly, is also a stupid idea.
Now that I've stated Donphan's problems, let's get to what that means for the deck: you need to find a way to take advantage of Donphan's tanking and low energy, while having an answer to Catcher. Most people make googlebox for this, but another option lies in Donphans and Dragons, which uses Donphan early, and outrage sweeps in the late game, using weakness to help it along the way. You absolutely have to keep Donphan alive however while keeping your opponent from setting up, both made harder with Eviolite and Eelektrik making Magnezone's lost burn more viable (and even Cyrogonal, to a lesser degree). Max Potion is a good idea, as it will heal off any damage that might result in a two shot. 3-4 Catcher is good, and you already have Rocky Helmet, which I think is a good play. Terrakion is a decent tech for the revenge kill since you can immediately build it up after swinging with Earthquake, but be aware of Catcher. I see little use for Tornadus in this deck as you aren't really weak to fighting (one selling point of Tornadus), don't need to build up attackers on the bench, not really (another selling point), and few pokemon are weak to colorless (the only other reason you would be running it).
If you want Donphan/Terrakion, I'd say make it a DnD variant so you can use Donphan's recoil to your advantage and have some of the best type coverage in the game, and I would definitely say run Max Potion so Donphan can stay alive. You're going to need it.
Having no strategy isn't good. It means that decks with a game plan will tear you apart while you're just trying to put damage on the field, and it also makes people less likely to post advice because, frankly, they don't know what your goals are, which is important to know in order to provide the best advice. Even an explanation of some cards would suffice. Rocky Helmet makes sense to me (put pokemon like Zekrom and Magnezone in range for Equake KO), but other people might not understand at first.
ill work on a stategy for you ill edit when im done 