Another question, will covet/thief still be in effect if the user is holding an item, thus the item will be given to the player instead?
[spoiler]
Generation II
Thief inflicts damage and has a high chance of stealing the target's held item if it is holding any. If the target is not holding an item or the user is already holding an item, Thief only inflicts damage and will not be able to steal an item. Held mailcannot be stolen.
The player's Pokémon's held item would not be stolen if Thief is used by a wild Pokémon.
Thief can steal a non-player character's Pokémon's items permanently. In link battles and the Trainer House items stolen will be returned at the end of the battle.
Generation III
Items cannot be stolen if the target has the Sticky Hold Ability. Like in link battles, items stolen in Secret Bases will be returned at the end of the battle.
In Pokémon Colosseum and XD, Thief does not steal items.
Generation IV
Thief will now always steal items under the conditions when they can be. All stolen held items will now be returned to the player if the opponent manages to steal an item by using Thief or Covet.
Items cannot be stolen from Pokémon with the Ability Multitype, and the Griseous Orb cannot be stolen. If the target's consumable held item is triggered by Thief, such as a Colbur Berry or Focus Sash, it will not be stolen.
[/spoiler]