You cannot get Gastly, Haunter, or Gengar in Pokemon Black without trading or transferring it from a previous pokemon game (i.e Platinum).
However in the Pokemon Dream World, by logging into the Pokemon Global Link website, and entering the Spooky Manor area, you can get a Gastly there. if you befriend the gastly (by reaching the target scores for the minigame it offers) it will be waiting in the Tree of Dreams at the end of your session. If you have any berry to offer (which can also be found in Dream world areas, usually noted by a multicolored sparkle) gastly will be added to your friend board (which can be found in your dream home) Next, wake your pokemon that you tucked in. the next time you play your pokemon black or White version, go to the entralink and you'll be transported to the center of the Unova region. enter the forest nearby and in the forest gastly will be waiting. you'll enter a battle, you can only use your bag in which there'll be a dream ball which will catch the gastly without fail.
to get the gengar, you'll have to trade haunter to either another black version or white version.
Haunter
You'll need to trade for a Haunter in order for it to evolve into Gengar.
You cant. You have to catch a gastly then envolve it to haunter then trade with someone and trade back haunter will envolve to gengar!
Have to train a gastly to evolve into haunter trade it to a friend and take it back boom its gengar.the only possible way to get a gengar in Pokemon fire red is to trade a haunter and then it will evolve into gengarThe only way to get a Gengar in Pokemon Firered Version is to trade a Haunter with another game.To actually have a gengar trade a haunter to a friend take it back to receive gengar. Agatha has two gengars if you want to see it.
in any Pokemon you evolve haunter by trading
Haunter
You'll need to trade for a Haunter or a Gengar in the GTS or from someone.
You'll need to trade for a Haunter in order for it to evolve into Gengar.
You trade haunter to get gengar.
Trade Haunter and you will get a Gengar.
To get a Gengar, you must trade a Haunter and it will then evolve into a Gengar.
Yes. The pokemon is Haunter. In order to evolve Haunter you will have to trade him with a friend and he will evolve. Just trade back to get Gengar.
you have to traid a haunter
There is no NPC who you can trade a Haunter to for a Gengar in Pokemon Crystal. To get Gengar you will need to trade with another player or a copy of Pokemon Gold, Silver or Crystal.
Gengar can only be obtained by trading a Haunter.
You can get gastly and haunter in lavender town. Trade a haunter to a friend to make it evolve into gengar.
Trade it!