K what I say might not sound totally helpful, but from a brief examination of the card, 3 options come to mind.
1. Twins (Tri). If you use Dusknoir's power, it get's knocked out. If you manage to get it set up early enough, you might be able to force your opponent to be ahead in prizes. If you use twins, you can take advantage of this by being able to immediately get any 2 cards, follow up by promoting a powerful attacker, possibly taking a prize that turn, and then doing 10 damage to all the opponent's pokemon immediately afterwards.
2. Gallade4 and Gallade4 LvX (RR). This is a line that I think might have some potential in a spread-based list (if that's what you're going for). Gallade4's attack does 20 for 2 energy (or 40 for 1 with expert belt and energy gain), plus 10 to each benched pokemon with damage counters on it. Gallade4 LvX has a power which allows you to put a damage counter on each opponent's benched pokemon when you place it down. With a few poke turns, you have the potential to do large damage to all pokemon in a few turns. It's not the best stratagy, but it could work.
3. As mentioned before by GoldenDP, Lunatone SV and Solrock Tri. Solrock has a body that prevents damage from being removed if there is a lunatone is in play. Using the SV lunatone is prefered as it prevents damage to both Lunatone and Solrock from all LvX pokemon (so Garchomp C and Luxray GL won't be as effective). This combination also gets around any Nidoqueen RR that you might encounter (which basicly cancels out your Dusknoir's effect). It's only problem (although not a problem just now) will be Pokemon Catcher when/if that get's released here, due to both of them having lowish hp (70). Also, Seeker, Super Scoop Up and PokeTurn will still get around it.