There is a boy in the Ilex forest (West of Azelia town) who gives you headbutt.
Headbutt is no a HM in Pokemon soulsilver. However a man in Ilex Forest will teach it to any Pokemon that can learn it.
headbutt trees
headbutt trees
By using Headbutt on a Tree.
use headbutt on trees
Headbutt dosn't come in a TM. You can teach a pokemon Headbutt by talking to a guy in a pink shirt in the Illex Forest. You can Headbutt trees (Like an HM) to find certain PoKeMoN.(It vairies where you Headbutt.)
It let's u battle Pokemon hiding in the tree
Many Pokemon can at the beginning if you choose totodile it can learn headbutt.
Any Pokemon can learn it. that's the best patr
Headbutt trees near mountains
A man in Ilex Forest gives it to you
(Improve) all i know is that slowpoke may know it.