>>16555111You're right on Azumarill, but not on Cloyster.
If anything from Pokebank could inheret Water Shuriken and breed it off onto something like Empoleon, that would break it up and bring its availability to dozens of other Pokemon.
Azumarill makes no sense since you can directly breed the two, but if Empoleon can get it, then if anything in the field group can get water shuriken, you've opened up dozens of potential Pokemon we outright couldn't test before.
All we know is nothing in the Water 1 group that's available can breed down water shuriken. So we just can't test other groups.