10 Worst Non-Signature Abilities In Pokémon Games
3. Klutz
Pokémon pretty much need to be holding an item to perform well in battle nowadays. Unfortunately, there are some Pokémon who cannot use items at all - Pokémon with the Klutz ability.
Before Generation V, the only Pokémon saddled with Klutz were Buneary and Lopunny, but that list quickly expanded as the Woobat line, Audino, the Golett line, and the Stufful line all gained access to it. Klutz prevents a Pokémon from using held items in battle.
While it does not negate the effects of certain items, such as the Cleanse Tag, the Soothe Bell (which makes evolving Buneary easier), and Mega Stones (if applicable), it cannot use other useful items such as berries and Leftovers. This ability also prevents a Pokémon from using Fling, so it can't even hurl an Iron Ball or something at their adversary.
The only possible way to make this ability useful would be to breed a Buneary with Switcheroo (because it is the only Klutz Pokémon that can learn that move) and make it hold some sort of harmful item like a Toxic Orb so it can immediately pass it off to opponents.
But that, much like Rivalry, feels like too much work for too little benefit.