I just read the article on headbutting. If you headbutt tree and there's no Pokemon, there will never be Pokemon on that tree...Wish I'd read it earlier. I was headbutting one for like 15 minutes. On the other hand, if there is a Pokemon there will always be a Pokemon on that tree.
Moveset: Rest, Sleep Talk, Surf, Hidden Power
Thanks ^_^
Got the Aipom, now I'm working on getting the egg moves.