Pickpocket

Steals an item when hit by another Pokémon.

Game descriptions

Black, White, Black 2, White 2:Steals an item when hit by another Pokémon.
X, Y, O.Ruby, A.Sapphire:Steals an item from an attacker that made direct contact.
Sun, Moon, Ultra Sun, Ultra Moon:Steals an item from an attacker that made direct contact.
Sword, Shield, B.Diamond, S.Pearl:Steals an item from an attacker that made direct contact.
Scarlet, Violet:The Pokémon steals the held item from attackers that make direct contact with it.