There's no need to explain why, it's frustrating to play a PvP, be about to win, you still got a counter vs Cloyster, and then, from nowhere, when cloyster just sets up Shell smash, tada, you get flinched!   It's literally one of the most unhealthy PvP items. For those who say that "King's rock is ok 'cause paraflinch exist eksdee", paraflinch can be stopped by lots of things like natural cure users, electric types, or heal bell cleric users, while king's rock cloyster is just a spammy