Well the shrimp won't help cycle..? I'm not sure what your thoughts were on that...Also they really don't clean the tank as they don't actually eat algae unless they're starved, they'll eat whatever's leftover by the axies though. I have ghost shrimp in my tank but you do need to quarantine them for 2-4 weeks. Also maybe look at the quality of the fish and stuff (namely like african dwarf frogs, I'd think whatever diseases they carry could more easily transfer to an axie as they're both amphibians) in the same tank at the store, if they don't look good I'd either wait and not get the shrimp or definitely quarantine for longer. If you're moving the same filter then I wouldn't expect a crash bigger than what you'd get with a regular water change when you might have to rinse the sponge or something.