So I wanted to ask if the Haunter and Gravler I have been training can be evolved but I still get to keep them?

Hello @Hektor047.

 

To evolve Haunter and Graveler, you are required to trade them. This, of course, means that another player would then take possession of them. However, if you make it clear that it’s to evolve your Pokémon, players return them. Make sure you ask them to not evolve it themselves and trade them back as their pre-evolved form so that you evolve them when you get them back.

 

Ask a player you trust to assist you in this. Make sure you always take screenshots of the agreement and trade, just in case they do not return your Pokémon.

Alternatively, you can ask Staff for assistance in your trade evolutions. Let me know in this thread if you would like Staff help. 
 

I hope this clears things up. If not, or if you have further questions, please let me know.