It is Gengar.
The pre-evolution of Haunter is Ghastly. To evolve Haunter you must trade it to Friend and have them trade it back.
Gastly > lvl 25 > Haunter > trade evolution > Gengar
Haunter
A Haunter has to be traded to evolve. You have to trade it without it holding an Everstone and it will evolve into a Gengar. The Everstone will stop the evolution process.
The way to evolve Haunter has been, and will always be, by trading. If you have a Haunter in Pokemon Emerald trade it to Sapphire, Ruby, Fire Red or Leaf Green and make sure he isn't holding an EVERSTONE as that will prevent its evolution.
The value of Haunter in the Pokemon games can vary depending on factors such as its level, abilities, and rarity. In general, Haunter is considered a popular and sought-after Pokemon due to its evolution into Gengar, so it can have value in both gameplay and trading communities.
It´s Gengar, it evolves from haunter (evolution of gastly) by trading.
Gastly > lvl 25 > Haunter > trade evolution > Gengar
In Pokémon Resolute Version, Haunter evolves into Gengar when it is traded. This evolution method is consistent with the mainline Pokémon games, where Haunter requires a trade to evolve into its final form, Gengar. Be sure to have a trading partner ready to complete the evolution!
My Friend code is 2794 0451 2472. I'll trade your Haunter for My Kadabra.
Haunter evolves into Gengar by trading. Since the GTS is not functional in Pokemon Diamond and Pearl anymore, you will need to ask a friend, who has a copy, to do a trade-back with your Haunter.
it does not evolve, you have to trade it first.Also if you trade your medicham for a haunter in snowpoint city haunter will not evolve to gengar because she gave it an everstone.not true- im not sure what level but my haunter evolved into gengar and the girl in snowpoint gave my a gengarIts not Gengar she just named is Gaspar because of how close it is and yea u have to trade