Yes, Heracross is a Headbutt mon. I'm also going to get a Shiny Adamant Shroomish from a Headbutt tree, I think in a Repeat ball :)
Well, the blocks simply suck. You have to wait for them. Changing the date does not work. But there's another option, which I use, because I simply am to impatient: an AR code. I'm not sure if I answered your question, though :P I didn't really understand what you were asking.