So here is my Keystone

It is on a pocket watch

The Pokemon that can mega evolve with it is my Blastoise... his name is Surf

His Mega stone looks like this

And it is on a crown like thing on his forhead

When he mega evolves he looks like this

Here are the rest of my Pokemon

Turtwig 👆

Chimchar 👆

I call him Torch 

Starly 👆

I call him Raptor

FieryFate