One-hit knockout move

One-hit knockout moves, commonly abbreviated as one-hit KO moves or OHKO moves, are moves whose effect is to immediately drop the target's HP to zero. When such a move successfully hits, the game will display the message "It's a one-hit KO!" (shortened to "One-hit KO!" in Generation I).

All OHKO moves have a base PP of 5. In Generation I, their accuracy was a constant 30%, but they would automatically fail if the user's Speed stat was lower than the target's. In later generations, they instead automatically fail if the target is of a higher level than the user, and their accuracy starts at 30% and increases by 1% for each level the user is above the target. For example, if the user is 70+ levels above the target, the move will have an accuracy of 100%.

The accuracy of OHKO moves is fixed to the above formula, and will not be affected by Accuracy or Evasion stat stages. For example, holding a Wide Lens will not make OHKO moves any more likely to hit, and using Double Team will not make them any less likely to hit. However, any effects that cause a move to completely ignore the accuracy check (such as the Ability No Guard, or X Accuracy in Generation II or earlier) will allow OHKO moves to always hit.

A Pokémon with the Ability Sturdy will be unaffected by OHKO moves, unless that Ability is negated (such as through Mold Breaker or Gastro Acid). A Pokémon with Wonder Guard is also immune unless it takes super effective damage from moves of the OHKO move's type. At full HP, a Pokémon holding a Focus Sash will instead be reduced to 1 HP by any OHKO move.

In the Mystery Dungeon games, OHKO moves can hit regardless of level, although they are very prone to missing as always. When one hits, the game states that the target fainted through "calamitous damage" (changed to the standard "It's a one-hit KO!" in Gates to Infinity). However, they actually do 9999 damage, which can be reflected with IQ skills such as Counter Hitter.

List of moves

Fissure	Guillotine
Ground	Normal

Horn Drill	Sheer Cold
Normal	Ice

Trivia

• These moves are often combined with Lock-On or Mind Reader to ensure it hits. Articuno can learn Mind Reader and Sheer Cold; in Generation II, Poliwrath can have Fissure and Mind Reader if it is taught Fissure in a Generation I game and traded over; and Smeargle can have any combination of the two types of move using Sketch.
• Lapras can learn the most one-hit KO moves of any Pokémon (excluding Smeargle), being able to learn Sheer Cold, Fissure, and Horn Drill.
• In Generations I and II, all one-hit KO moves were normally ineffective against a type of Pokémon. Fissure could not affect Flying-type Pokémon, and Guillotine and Horn Drill could not affect Ghost-type Pokémon (barring moves like Foresight). Sheer Cold (introduced in Generation III) broke this pattern, as no type is immune to Ice-type attacks.
• Due to the ability of Aerilate introduced in Generation VI, if a Pokémon possesses it, Horn Drill and Guillotine are made into Flying-type 1-Hit KO moves as opposed to Normal-type. This bypasses the immunity Ghost-types would normally have to Horn Drill and Guillotine, negating the need of Foresight.

This article is part of Project Moves and Abilities, a Bulbapedia project that aims to write comprehensive articles on two related aspects of the Pokémon games.