I just found a good way to use Dark dugtrio in a deck.
 
Hitmontop -Promo #37
2nd Attack
Rapid spin-if your opponent has any benched pokemon, they choose one of them and switches with their active pokemon, then if you have any benched pokemon, you choose one of them and switch it with your active.
2 fighting, 1 colorless energy costs
 
Dark Dugtrio
Pokemon Power-whenever your opponents active pokemon retreats they flip a coin.  If tails, this power does 20 damage to that pokemon.(don't apply weakness and resistance)  This power stops working while dark dugtrio is asleep, confused or paralyzed.
 
If you have hitmontop as your active and more hitmontop on your bench and a dark dugtrio, and you use rapid spin then it has a chance to do up to 50.  This Dark Dugtrio power can also be used with dark machoke.
 
-fRed