Not to cut in, but do you have Shelmet or Karrablast? They become Accelgor and Escavalier respectively when traded for each other, both evolving provided neither holds an Everstone (since Escavalier's shield comes, I think, from Shelmet's shell, and there's some aspect of Accelgor that comes from Karrablast).
If you trade those, then trade them back, you cover the Pokédex for all four in the two trades even if you only had one to start with. :)
Both are found in Routes 14 and 19, so if you need someone to trade back and forth with, I can assist. I'll trade something to you, then we trade the two, then we trade the EVOLVED two again, then I finally get mine back when I send whichever one I have back for it. I'll use a Friend Safari catch if there's anything you want to get in your Pokédex, and this would clear both evolved forms from mine. Or I can catch one and you the other and we just trade twice. Whatever you want. :)