Which Pokemon can you get using Headbutt in Pokemon Crystal?

AnswerIf you use Headbutt on a tree in Pokemon Crystal, one of the following Pokemon may appear:

Spearow

Heracross

Aipom

Ekans

Hoothoot

Noctowl

Spinarak

Pineco

Ledyba

Exeggcute

Venonat

Caterpie

Metapod

Butterfree

Weedle

Kakuna

Beedrill