Bagon/Horsea: Dragon Scale
Zigzagoon: Oran Berry
Linoone: Sitrus Berry
Aron/Lairon: Hard Stone
Dusklops/Duskull/Bannette: Spell Tag
Cacnea: Poison Barb
Trapinch: Soft Sand
Magnemite: Metal Coat
Skitty: Leppa Berry
Pikachu: Light Ball
Sandshrew: Quick Claw
Staryu: Star Dust/Star Piece
Koffing: Smoke Ball
I hunted some of these items with my shiny Linoone and Covet. This is the best way to hunt the items. Just use Covet, then kick butt!!! Make sure to check Linoone for Pickup items in case the pokemon isn't holding an item.
Numels, Linoones, and Luvdiscs hold their respective (Common) items 99.9% of the time! Linoones, on occasion, are holding Sitrus Berries!
Pokemon like Poochyena, Whismur, and Kecleon have a small chance of holding Chesto Berries. If you've used up all of a particular berry, these pokemon can prove to be a boon.Girafarig might also hold Persim berries.