Klutz

Klutz prevents the Pokemon from using or benefiting from its held item in battle. While Klutz is active, the held item has no passive effect — berries will not activate, Choice items will not boost stats or lock moves, Life Orb will not increase damage, and type-boosting items will not apply. The Pokemon also cannot use the move Fling while Klutz is active (though in Generation V, this restriction was briefly removed). The item is not removed — it simply has no effect.

However, there are notable exceptions. The Speed-reducing effects of Iron Ball and the EV-training Power items (Macho Brace, Power Weight, Power Bracer, etc.) still apply even with Klutz. Moves like Natural Gift and Switcheroo also function normally, allowing the Pokemon to pass its unusable item to an opponent — this is actually Klutz's primary competitive niche. A Klutz Pokemon can hold a Flame Orb, Toxic Orb, or Iron Ball and use Switcheroo or Trick to dump the negative item onto an opponent without suffering any penalty from holding it themselves. All items work normally outside of battle. Found on 12 Pokemon including Lopunny, Buneary, Wobbuffet, and Audino, Klutz has been available since Generation IV.