You have to get a haunter by trade or in the cave giratina is in which would be route 214 spring path. Then you have to trade your haunter I don't think it needs any items, and it'll evolve into a gengar! But that's the only way people have found out to do it so far. Hope it helped!
You can also catch a gengar in the old chateau. But, you must have inserted in you Nintendo DS Pokemon fire red, Pokemon leaf green, emerald, ruby, or Sapphire. you climb the stairs and got through the door directly in the middle. the you look for a room with a frame on the wall that looks like its eyes are glowing. in that you can find a gengar. i caught mine at lvl 17. Male. its much easier than trading.
you can't catch a gengar. you catch a haunter then trade it so it evolves. make sure its not holding an everstone. ;)
You cant catch Gengar in there, only Gastly and the Rotom in the tv.
gengar cannot be caught in diamond or any other game it can only be obtained via trade or action replay code for stealing pokemon.
gengar cannot evole :P
Gengar can only be obtained by trading a Haunter.
There is no place that you can catch a Gengar and he can only be obtained by evolving Haunter via trade.
gastly, haunter, gengar
Drifblim, Gengar, and Mismagius
you get him someow in the lost tower
Sorry to say, but Gengar is not obtainable in the wild.
you trade him. and he will evolve into gengar. you trade him. and he will evolve into gengar.
You can't find gengar in the wild, you have to get a haunter and trade it.