Ability Detail

Klutz is an ability in the Pokémon series that has a unique and somewhat niche effect. When a Pokémon with Klutz is holding an item, the effects of that item are entirely negated in battle. This means that beneficial items such as Berries, Leftovers, Choice items, or any other held items will not provide their usual benefits. However, it also means that detrimental items, like the Iron Ball or Flame Orb, will also not activate their negative effects.

Here are some detailed points about Klutz:

Negation of Held Items: Klutz completely neutralizes the effects of any held item. For instance, a Pokémon with Klutz holding a Life Orb won't receive the usual power boost, but it also won't take the recoil damage that normally comes with using a Life Orb.
Strategic Uses: Although it may seem like a purely negative ability at first, Klutz can be strategically employed. For example, a Pokémon with Klutz can hold

Effects

In battle, this Pokémon cannot use its held item, nor will the item have any passive effect on the battle, positive or negative. This Pokémon also cannot use fling. The Speed cut from the iron ball and the effort items (the macho brace, power weight, power bracer, power belt, power lens, power band, and power anklet) is unaffected. Items that do not directly affect the battle, such as the exp share, the amulet coin, or the soothe bell, work as usual. All held items work as usual out of battle. Other moves that use the held item, such as natural gift and switcheroo, work as usual.

Flavor Texts

diamond-pearl: The Pokémon can’t use any held items.

platinum: The Pokémon can’t use any held items.

heartgold-soulsilver: The Pokémon can’t use any held items.

black-white: The Pokémon can’t use any held items.

black-2-white-2: The Pokémon can’t use any held items.

x-y: The Pokémon can’t use any held items.

omega-ruby-alpha-sapphire: The Pokémon can’t use any held items.

sun-moon: The Pokémon can’t use any held items.

ultra-sun-ultra-moon: The Pokémon can’t use any held items.

lets-go-pikachu-lets-go-eevee: The Pokémon can’t use any held items.

sword-shield: The Pokémon can’t use any held items.