Headbutt is a Normal-type damage-dealing move.
Headbutt inflicts damage and has a 30% chance of causing the target to flinch.
Out of battle
The use of Headbutt requires the Pokémon knowing the move to have 150 or more Happiness. However exceptionally, the Headbutt Trees in Pallet Town, Route 1 and all Sinnoh areas do not require the Pokémon to have any happiness.
Headbutt can be taught from a Move Tutor from most early region forests, the only exception being Hoenn's Petalburg Woods. In Viridian Forest, the tutor will be hiding in the south-west corner of Viridian Maze, will require Pewter City's Boulder badge and will cost 2,000. The two other forests, Ilex Forest and Eterna Forest, do not have any requirement and are cheaper at the price of 1,000. They are also fairly close to the main path and easy to find.