I want to find a good way to play this deck/card so badly, but I simply don't think it has the attack power! Sure it's annoying, and with an Energy Gain, you can get it attacking turn 2/3, hopefully have a Snowpoint out, and, a Shaymin Lv X, either with level max or switching...
It has potential in my eyes and I'm just waiting to see an awesome decklist pop up for it somewhere.
I don't see Cherrim working in this deck. I would probably play it with Claydol and maybe 1 or 2 Uxies for quick setup, to get all the necessary cards. So if I have a Turtwig, a Shaymin, a Claydol, and a Uxie down, I can maybe have 2 Cherrims out if I can get it set up? But naturally I would like to have atleast 1 Turtwig on my bench being built for when the active dies or I have to switch. You know what I mean? I might be thinking too much into it but that would be my main concern with Cherrim.