Why does Gengar break every format he's printed in?

[Mac Sting]

Gengar breaks the format every time he's printed?

Gengar DP sucked horribad, and no one plays LostGar.. Only good Gengar is the SF lately and Cursegar.. Even the Sharpshooting Gengar was horribad.

 

[Lumneion]

The reason why it's good is because it looks cool.
I mean, thats why people play LuxChomp, because Luxray and Garchomp look cool, right?

 

[Chromecatz]

The question is why has almost every single genger been tournament playable while some pokemon have never been made into a competitive card?

 

[ShuckleLVX]

^WTB Shuckle.dec^

 

[Scipio]

The better question is why were there as many Gengars in 4th gen sets alone then there have been Kangaskhans in the entirety of the game? >.<