Yeah, I hate this match-up so much...
I've found the best way to approach snake in this match-up is to keep him in the air as much as possible, as difficult as that is. I personally learned the hard way not to pick his grenades up, because a good snake will strip them before you get to throw them back. Yeah desynced, IBs will interrupt his mine placing, but for the most part thats not a camp battle the Iceys can win.
At mid range most snakes will want to snake dash you to death. DO NOT make the mistake of trying to grab him at the end of this. As tempting and easy as it is, you'll simply get punished by a falling mortar every time (unless you can manage to chaingrab him out of the way in time, something I have never been successful at
)
Close range is all about being unpredictable. Most snakes (well, I guess all characters) when fighting the ICs pretty much watch out for one main thing when we approach, the grab. This of course means they'll be shield dropping grenades left and right or cooking them whenever they feel in danger of a grab.Just be careful, bc if you miss a grab or fail with a punishable move, you're pretty much guaranteed to be eating a Ftilt with a side of about 20%, spacing you once again for the camp game...
If you do manage to get the opportunity to CG him, try to get him near the edge and Dthrow>Fair spike him and go for the snake gimp...
As far as counter pick stages go I am completely clueless...I sometimes try to go somewhere with a high ceiling to avoid death by Utilt or any of the explosives, like Jungle Japes.
I guess that was more of what not to do than what to do, but thats all I have...