Where do I get the stone that Mega evolves Garchomp?

Question

I don't know what it is called, probably Garchompite or something silly.

Answer 1

You get it in victory road. Make sure you have rock smash and its between 8pm and 9pm.
Just follow this video to find it: https://www.youtube.com/watch?v=EhC8uSrcvUQ