[Scripting Question] Trading for a Specific Ability

How do I create a trade where the NPC would like a mon with the ability Thick Fat in return?
I can't figure out how to set it up.

How do I do a Trade with a special condition?

Try searching next time. This thread is only 10 below your one (at time of writing)!

I appreciate you pointing me in the right direction, but there's not enough information given in that thread for me to find a solution. I don't know what to actually script into the Pokemon selection to make the game check for specific abilities.
Trying to use .setAbility doesn't work.
.hasWorkingAbility returns an error.

Have you tried with ".hasAbility?" ?

https://www.pokecommunity.com/showthread.php?t=416314

This doesn't work either, unless I'm just doing something wrong.

It doesn't work in what sense? You get an error when it runs? Or a syntax error perhaps? Or it just doesn't do anything at all?

People aren't mind readers, you have to help us.

Maybe you can use

That did the trick. Thank you!