Klutz prevents the Pokémon with this Ability from using Natural Gift; however, it does not prevent the Pokémon from using Fling. If a Pokémon with Klutz uses Bug Bite or Pluck, it will consume the target's held Berry without gaining its effects. If a Pokémon with Klutz uses Judgment, it will be a Normal-type move.
All effects of the Iron Ball are now negated by Klutz. However, Klutz still does not negate the Speed drop from the Macho Brace and Power items. Klutz cannot negate form-changing effects of items, but will still negate the other effects of those items (e.g. if a Giratina holding a Griseous Orb has Klutz, it will remain in its Origin Forme, but will not receive the 20% boost in the power of Dragon- and Ghost-type moves).
Klutz prevents the effects of the held item from applying.
In Pokémon Super Mystery Dungeon, it also prevents the Pokémon from using or throwing items. This effect does not apply if the Pokémon is the team leader. Additionally, Klutz prevents the Pokémon from being afflicted by the puppet status condition.