Many people use Indra to farm from
Munchlax is anther option with thief, recycle, fling, covet and as Snorlax it learns yawn if you want to go that route
Delphox magician ability, recycle, switcharoo, a move of your choice then a status move or attract (steaks item when is attacked, use switcharoo/fling (this damages the Pokemon it's flinging it to) to return item, use recycle to get the item back then not 100% need the status so you could choose 2 moves instead of 1)
Klefkei if magician recycle, switcharoo/fling, and two there moves you want to move second here
If prankster recycle, covet/thief/switcharoo, thunderwave/attract and one other move of your choice
Gothitelle Frisk recycle, thief/covet/Trick, fling, thunder wave/Attract/trick room your choice or go for an attacking move as Gothitelle has pretty bulky defensive stats or run Claydol who has even bulkier stat in defence
Heart scales are from wild lovdisc I would suggest having something with compound eyes at the front of your party Butterfree works wonderful since it can learn thief also can get from mining rock common enough also find a few naturally if you want check out the linked guide in my signature
Depending on how late in game you are there are 2 leftovers in the renovated city in the cafe in North Obsidia and 1 on muchlax for qwilfish in calceleon city