The only snails that can be kept with axolotls, assuming the axolotl is over 5in in length, are bladder/pond snails. Apple/mystery snails are way too large and will cause problems because the axolotls will try to eat them. MTS and large ramshorn snails are also problem snails because they tend to have very hard shells and can cause internal damage or impaction. To an axolotl a snail is a snail so most will almost always try to eat anything they think is food.