>>34782639What you need to do is sos chain the Ditto like normal, using the AFK Smeargle method. Then, once you reach 30-40 chain, send in a specific A-Raticate.
This specific A-Raticate only has hidden power Fighting as its only move. When a Ditto comes, let it Impostor, or Transform into your Raticate. Then, let your Raticate tank whatever Hidden Power the transformed Ditto hits it. As Normal/Dark, A-Raticate only resists Dark moves. If you see the move as anything other than 'Not Very Effective' kill the Ditto.
If your Raticate gets hit by the HP and resists it, kill the Smeargle/Ditto and quickly Spore the A-Raticate/Ditto and catch it. It only have 5PP on Hidden Power, so make sure to catch it quick.
Tips, make sure that your Raticate is more than level 44 so that it doesnt learn a new move which isnt Hidden Power while SOS catching. Give it leftovers and max out its HP and SpA. HP fighting is important to that you one-shot opposing A-Raticate/Ditto. Also, make sure your Ditto is Gluttony, not Hustle which will make the grind a lot more annoying.