You have to trade it to evolve it.
You will need to level up Haunter to level 50 to evolve it in Pokemon Resolute.
Either level 24 or 25. It evolves into Haunter but then if you want a Gengar, you have to trade with someone and then it will evolve and then trade it back. (Make sure they give you a good Pokemon as collateral so you get it back!)
Prinplup evolves at level 36
Haunter evolves through a trade.
Gahstly will evolve at lvl25 to Haunter then trade haunter to evolve to a Gengar.
Gastly evolves into Haunter at level 25, then trade it and it will evolve again into Gengar.
you have to trade
You have to trade haunter to a friend to evolve it.
no level you have to trade dude
Haunter will evolve into Gengar when it is traded. It doesn't matter what level it is, just trade it with someone and when they get it it will evolve into Gengar, then get them to trade it back to you.
Haunter can level up and evolve. It evolves by trading with another player.
You have to trade the Haunter to evolve. I learned the hard way. It got to level 59 and I traded..... it evolved!