Calcs come up with... if the Crobat has no HP or Special Defense, it survives with about 11% remaining. So it could revenge kill if everything goes normally.
Ok, this Im kind of throwing out there, but I like trying stuff out. So, for a Skymin counter we have
Mamoswine
Item:Choice Band
Ability:Snow Cloak
Ice Shard
Icicle Spear
Earthquake
Stone Edge
Nature:Adamant
EVs:252 HP, 252 Attack, 4 SpDef
Ok, well, its untested, but heres how Im thinking it works. Its a revenge killer, and has trouble with Specsmin, but hear me out. Icicle Spear is a move that can hit in between 2-5 times with 10 damage each time. If it hits 2 times, it destroys a Shaymin sub and do damage, 3, does a even more amount of damage, and 4-5, can kill depending on how many subs were used. It can survive only ONE no stat increase Seed Flare, Air Slash 3HKOs without flinch hax, and Earth Power 4HKOs. For the times it isnt under a substitute, Ice Shard deals An OHKO. The only big problem is how Specsmin can OHKO with a Seed Flare, but Ice Shard stops it cold.
Now consider this, Icicle Spears accuracy for each hit it 100. So, with no evasion changes, it could almost always kill. Any thoughts?