Yes. This tip is quite old, I'd actually bump my old thread, but I can't seem to find it... but whatever! xD I'd just like to inform people that they do NOT have to trade their precious Haunters and Kadabras to people they might not trust fully. Here is how you'd do so...
Go to the GTS and offer the pokemon for something, like a legendary.
Then, go look around for a simple trade, for like a Bidoof, if you can find one that is... it's so hard to find decent trades now.
Anyway, once you are done trading with the person, go back to check on your pokemon, when you take it back from the GTS, your pokemon should evolve should all of its conditions be met. Like a Scyther holds its Metal Coat and such. ;)
Anyway, hope this helps people, and don't get mad if your pokemon gets taken, it's just a risk. ;)