Read somewhere that Cursed Body has a 33.3 % chance to work, but that's not confirmed yet, I think - but it's sure that it doesn't work all the time.
Oh, that's god, means that Cloyster doesn't have to risk being forced to switch when attacking.
Although Desukan will probably force a switch too, removing Skill Link would make Cloyster RNG hell until is swaps out.
Bulk isn't very kind to Cloyster.