a piece of cheese
You wil have to trade with FireRed or XD.
Cloyster can only be obtained through evolving Shellder. Shellder is a FireRed-exclusive Pokemon in Generation III.
Shellder can be found in firered and leafgreen either you fish for one or look in seafoam islands.
I know firered can, if you seen a shellder look at it on your pokedex and check its area if it says unkown you will HAVE to trade a shellder to leafgreen from firered.
Use a good rod in seafoam islands.
You can catch shellder in Pokemon red, blue, yellow, gold, silver, crystal, FireRed, XD, diamond, and pearl.
Poliwhirl → Poliwrath, Shellder → Cloyster, Staryu → Starmie and Eevee → Vaporeon
u hau have to trade a shellder from firered and then evolve it w/ a water stone.
lombrea, evee, poliwhirl, shellder, and staryu. some of these can only be found in firered and leafgreen so you will need to trade. that's all I can think of.
Pallette Town with the Super Rod. (Yes, you need the Super Rod in Fire Red.)
you can't get a shellder in leafgreen, you can only get it in firered. you can ask a friend that has that game to catch you a shellder and trade it to you.
you cant you can only get shellder in Pokemon fire red version sorry about it it made me mad to