As far as countering Gengar [Prime and SF\AR], would a deck that uses lines of Dialga G lvl.X, Umbreon UD, and Mightyena LA, work well.
The You could use Umbreon to attack for the first part of the game, then switch to Dialga G and Deafin lock so they can't play any Stadiums when you are high in the Lost Zone count.
Mightyena could be used for Regigiagas maches and assist a bit in SP match ups.
Dialga G could also be used for an E-belted hit on Gyrados for your first 30 then use a Devoluter TM, to knock out the Magikarp. This would would also still send the karp the the discard instead of their hand incase of Rescue energy; since it was an effect not damage.
Your Machamp Match up would be hard, and your SP match ups will be Diffcult.
You could take out the Mighyena and put in a 2-1-2-1 Dusknoir[Damage Even\Night Spin] line, this should help you more your Machamp match ups and your SP match ups as the Night Spin is deadly to the SP who rarely have 3 energy attached due to E-Gain. Then with a Dusknoir Lv.x in play while your oppnet is under Trainer\Stadium lock can be a deadly spread to benched techs, and damaged poke's. This will do an amazing [W|E-belt\W|out]
50\30 to the active and 20 to all benched each turn.
I prob. will be playing this deck or a varient of it at states at States.
Now the hardest part of makeing a rouge deck.....What to name it?