I have the following Megastones to trade for it:
Blastoisinite
Kangaskanite
Gyaradosite
Mawilite
Venusarite
Aerodactylite
If intrested i also have a Shiny Venusaur. It's not very competitive as it only has no egg moves, overgrow ability 5IV's, but not perfect in Sp.atk. and has impish Nature.
If you find more of interest on the list, i am also interested in Charizardite X aswell, but the priority isnt THAT high.
what do you have to trade for it??