How do you have your Cloyster Ev'd. Fake Out + Low Kick from ambipom spells death to mine... otherwise he would make for a tremendous lead.
http://www.smogon.com/forums/showpost.php?p=2261810&postcount=59
I just switch out to Arcanine against a lead Ambipom though. Ambipom doesn't set anything up, therefore there is no long-term consequence to switching out of it. Cloyster excels against setup leads, or just powering through others with strong attack + sash + priority.
Ambipom can only OHKO with Low Kick after Fake Out because it is glitched. Kinda ridiculous really, even Registeel can be 2HKO'd like this at the moment.













