Some lady in a city will trade you it but it will stay as haunter.
You trade haunter to get gengar.
Haunter evolves when traded
Actually, Haunter does evolve. Its evolves into Gengar when you trade it.
Haunter evolves only by trading to another game.
gastly, haunter, gengar
you get it over a trade.
Nothing, to evolve haunter you have to trade him...
25 into Haunter and then if u trade Haunter he evolves into Gengar
turn back cave
trade
yes
You trade Haunter it it will become a Gengar.