I do find it pretty cool that he's ALWAYS been OU. Only him and Starmie have done that IIRC.
Gen I: Sweeper with Hypnosis and other popular special moves Gen II: Same Gen III: Levitate makes him quite a bit better Gen IV: Physical/Special split means he now has a dangerous STAB move Gen V: New tricks added to his arsenal, like a better Disable. Gen VI: Can hit Steel hard now and resists Fairy
As OU progresses they keep making Gengar better.
I'm not against religion. I'm against all bad ideas, held for bad reasons, prompting bad behavior.
Since this is a Gengar appreciation topic, I thought I'd share my favorite Pokemon experience...which happens to involve Gengar.
This is back in the Gen 1 days. I was battling against a friend who caught Missingno in its Lv. 350 Snorlax form. He was bragging before the battle, "You can't beat me! I have a level 350 Snorlax, you have no chance!"
Remembering Ghost's resistance to normal attacks (remember, this is when Pokemon strategy was learned through the game itself, word of mouth, and paying $15 for player's guides), I plopped Gengar into the 6th spot on my team. I hardly ever used Gengar before. In battle, the Lv. 350 Snorlax outsped my Gengar and used Hyperbeam. It obviously had no effect and my friend yelled, "What!?!?!" I then proceeded to wreck the Lv 350 Missingno-Snorlax with Night Shade! It was so satisfying.