18.
Was going to vote this down on design. Read its Pokedex entries. Shares the Shield entry: "Klefki sucks in metal ions with the horn topping its head. It seems this Pokémon loves keys so much that its head needed to look like one, too. "
Knew about it not being a solid keyring. Never perceived it as having horns, however. Feels less like an object Pokemon and more of the Klefki's conscious choice. Misunderstood it, in a sense. Seems far more interesting now.
(Also happens to be very useful in battle. Prankster, a ridiculous defensive typing, and good support moves? Very yes.)