One Hit KO Moves
Pokémon moves in general are a simple calculation of stats based on the user, the opponent and the attack itself. However, there are four attacks that are guaranteed to completely wipe out a Pokémon whenever they hit. These attacks are the One-Hit KO Moves.
No matter what the Attack or Special Attack stat is for the Pokémon using it nor the Defense or Special Defense of the opponent as well as the Hit Points of them. Whenever this move hits, no matter what the status of the Pokémon is, their HP will be taken down to zero and they will faint. This makes these attacks the most powerful attacks in the game
There are however, a number of drawbacks to these attacks. Firstly, their accuracy is set at 30%. This can be augmented therough various means such as items and attacks. The Mind Reader/Sheer Cold combo is a classic one. Three of the four moves will also suffer from certain typed Pokémon not being able to be hit by them without intervention from attacks. For Fissure, you cannot hit a Flying type and for Guillotine & Horn Drill, you cannot hit a Ghost type.
There is also the fact that if your Pokémon is of a lower level than your opponent, the move will not connect at all, essentially having a 0% accuracy. Pokémon with the Sturdy ability are also immune to One Hit KO moves. Other than these drawbacks however, the One Hit KO moves can be used very well by the Pokémon knowing it. Below is a list of the moves and the Pokémon that learn them in Diamond & Pearl