Pallette Town with the Super Rod.
(Yes, you need the Super Rod in Fire Red.)
You wil have to trade with FireRed or XD.
Use a good rod in seafoam islands.
Poliwhirl → Poliwrath, Shellder → Cloyster, Staryu → Starmie and Eevee → Vaporeon
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.
You cant find it in Firered only leafgreen.
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.
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.
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.
bob
in route 201
find a shellder in the water of pallet town then give it a water stone