Horn Drill

Function

Horn Drill inflicts damage equal to the target’s current HP, guaranteeing that it faints if the move hits. It’s accuracy is based on the difference in level between the user and the target, using the following formula:

Acc = ( ( user_level — target_level) + 30 )%

This means that the accuracy is 30% at equal level, and increases by 1% for every level of difference, reaching 100% accuracy with a level difference of 70. Furthermore, accuracy and evasion changes do not affect Horn Drill’s accuracy.

If the target is higher level than the user, or if the target has the Sturdy ability, Horn Drill will always fail.

Ranked PvP

The use of Horn Drill is forbidden in Ranked PvP as per the OHKO clause.

Bugs

Unlike in the original games, Horn Drill does not make contact. It does not trigger on-contact abilities and items like Rough Skin, Static and Rocky Helmet. (Report thread)
If the opposing Pokémon blocks Horn Drill with the Sturdy ability, the regular ‘But it failed’ message is displayed, not informing that it failed because of Sturdy.

Learnset

Level-up

No.	Type 1	Type 2	Level
032	Nidoran Male	Poison		45
033	Nidorino	Poison		58
111	Rhyhorn	Ground	Rock	53
112	Rhydon	Ground	Rock	62
118	Goldeen	Water		37
119	Seaking	Water		40
464	Rhyperior	Ground	Rock	71
530	Excadrill	Ground	Steel	31
696	Tyrunt	Rock	Dragon	49
697	Tyrantrum	Rock	Dragon	53
Emboldened Pokémon avail from a STAB bonus for this move.

Egg Moves

No.	Type 1	Type 2
077	Ponyta	Fire
078	Rapidash	Fire
086	Seel	Water
087	Dewgong	Water	Ice
131	Lapras	Water	Ice
Emboldened Pokémon avail from a STAB bonus for this move.