Evade/Accuracy

One-hit KOs

Paralysis

If successful, these moves cause the enemy to faint, regardless of their HP, Defense, or Special statistics. Ordinarily, one-hit KO attacks have a 29.7% chance of success, but Azure Heights researchers have determined that a Pokémon's vulnerability to these moves depends on its Speed, relative to the attacker. Specifically, it is known that:

1. Pokémon A will be only be able to affect Pokémon B with a one-hit KO attack if A's Speed is equal to or greater than B's. The relative Speed required for success with one-hit KOs is a matter of actual Speed, not "base" Speed. Thus, a 30th level Dragonair may be unable to affect a 40th level Kadabra with Horn Drill. However, as the Dragonair gains levels (and Speed), it will eventually be able to affect that particular Kadabra.

2. Attacks that alter Speed can alter vulnerability to one-hit KOs. In the previous example, if Dragonair knew Agility, it could negate Kadabra's immunity by boosting its Speed sufficiently. If Dragonair knew Thunder Wave, it could also negate Kadabra's immunity by paralyzing him (which produces a drastic reduction in Speed). Conversely, a Pokémon vulnerable to one-hit KOs may be able to achieve invulnerability by speeding itself up, or by slowing its opponent down (again, success at these endeavors ultimately depends on the relative Speeds of the Pokémon).

3. Speed alteration cannot be used to increase the chance of success with one-hit KOs beyond 29.7%. Just because you have a Rapidash with Agility and Horn Drill, don't expect to somehow achieve an 80% success rate.

If a one-hit KO successfully hits an opponent's Substitute, the sub will break.

Guillotine and Horn Drill are functionally identical. Because they are Normal attacks, neither can affect Ghost Pokémon.

Fissure can KO Ghosts, but it can't affect Flying Pokémon (due to its Ground type). Otherwise, it works just like Guillotine and Horn Drill.

So when choosing between Horn Drill and Fissure for your Mew, you'll have to decide which you fear more: the speedy Gengar or the (mostly) not-as-quick Flying Pokémon in the game.

None.