Used this strategy (Thanks a bunch BTW) but brought level 14 Tainted Rat and switched him in / out when I would have passed twice with with my snail. Continued as strat suggested all the way thru. Got 5k + xp and leveled the rat to 18. Thanks for sharing :)
Both S/S Breeds works, too. Unfortunately didn't find a way to get a LvL1+-Pet through. If you swap it in after Snails death the Rabbit rota is broken. Btw, mine was a Rare Whelk S/S...so Rapana works.
Unfortunately the Any Snail refers to any named snail. Most snails have multiple breeds and each fight may depend on breed. So I'd try other snails you have with different breeds to see what breed works. If i get a chance later I'll test this as well. And put a note on the breed that worked for me.
The reason you pass on those turns is that you are not doing any actual damage due to the Stone Form, but you are taking damage from the Spiny Carapace. So you land up in a worse position than by passing.
I had a variation when I tried it today. Rabbit Turn 2+ reads "Scratch until Slow Moe is dead (should be 1 or 2 turns)". In my case it was one turn because of a crit. This left me unable to Dodge Snot's Dive because it was not yet off CD. I won with the rabbit anyway, but if this happens, Snot should be at very low health for your third to finish off.