I am King Gengar, so Gengar is King, right? Not exactly.
Loses to Dark, so Shiftry has a chance, as does anything that runs Weavile SW.
Gengar will see its share of Glaceon Lv.X as Eeveelutions becomes popular again.
Amphytric isn't exactly dead, and Amphy itself has good combinations.
But is Gengar GOOD? oh yes!
Best or one of the top 2 or 3 best snipers in the game. No Retreat. Wicked Poke-Power lets you win for losing. The reason is CAN be best BCIF is because it actually loses! haha
But let us not forget Pitch-Dark which makes Gar-Champ one of the most formidable decks out there. Mother Gengar is good, but not AS good, IMO. Gengar/SP hybrid is a good deck. In fact, King Gengar (with Kingdra) is supposed to be pretty good (go figure).
Enjoy 9/10