Ultra-sun: If areas of Cloyster’s very hard shell get damaged, those areas swell, gradually growing into large sharp spikes.Moon: Excavation of the tombs of ancient hunting tribes has turned up many spears tipped with spikes that had fallen off this Pokémon’s shell.Alpha-sapphire: Cloyster is capable of swimming in the sea. It does so by swallowing water, then jetting it out toward the rear. This Pokémon shoots spikes from its shell using the same system.
Prof. Lotus' Notes: There's no denying that thus Pokemon resembles a very specific body part. And the 'clam' aspect of it ultimately makes it the perfect double entendre. The change in shiny colour is even further futher linked to it. It could have been Gold like it's pre-evolution but it's blue reminds me of... Waffles? PLEASE DON'T GOOGLE THAT.... You heard it here first.