Cloyster was not in the original Gen IV pokedex, but it is now available in the remakes.
Looking at datamining sites, I found these capture locations for its pre-evolution (Shellder):
Location | Method | Level |
---|---|---|
Route 205 - South | Super Rod | 20 - 40 |
Valley Windworks | Super Rod | 20 - 40 |
Fuego Ironworks | Super Rod | 20 - 40 |
Grand Underground - Fountainspring Cave | Underground | 58 - 63 |
Grand Underground - Riverbank Cave | Underground | 58 - 63 |
Grand Underground - Still-Water Cavern | Underground | 58 - 63 |
It seems that the Super Rod can only be obtained after defeating the Elite Four.
So, is that the soonest I can get a Cloyster or is there any other way to get one?