How do you get the reaper cloth in Pokemon Emerald?

I'm not completely sure, but I think that you can only get a Reaper Cloth in Diamond and Pearl, because Duskonoir is a Sinnoh region Pokemon.

yeah he's right. you will hav to stik with dusclops because duscnoir wasnt created when emerald came out. he's a new Pokemon for the sinoh regon ( diamond pearl .) but if you get him in d or p i sugjest not to evolve him till he knows moves you like because he cant learn any new moves after evolution. hope this help you!