easy u go to fire area in the corner
Around kanto certain fisherman give you fishing rods.
You can't get a Tentacruel by just fishing/surfing in Pokemon FireRed. You have to Evolve a Tentacool (It evolves at level 35).
Because there's water in celadon city if you use fishing rods in the water you can actually find pokemon!
Simple find a good rod from a fishing guru and go to the shore of island 6 and use it until you get horsea. -PokemonAnswerMaster-
You cant find it in Firered only leafgreen.
Staryu is a water type Pokemon. In Pokemon FireRed, it is possible to find lots of Staryus in the Seafoam Islands.
You cannot find Piloswine in the wild on Pokemon FireRed. You can find it's pre-evolved form Swinub in Icefall Cave on Floe Island in the Sevii Islands of Pokemon FireRed.
Celebi cannot be found in Pokemon FireRed. The only way to get Celebi in Pokemon FireRed is receiving it from an event distribution. These events are sadly no longer supported for Pokemon FireRed.
It's not possible to find Sudowoodo in Pokemon FireRed. You will need to trade for one from a Pokemon Emerald game-save.
Yanma can't be found in Pokemon FireRed or Pokemon LeafGreen; it is strictly a fourth generation Pokemon.
Which game? Grimer > lvl 38 > Muk In Firered and Leafgreen you can find them in Celadon City by fishing, but that is pretty rare, and the Pokemon Mansion eveywhere.
You can find TM Dragon Claw on Victory Road in Pokemon FireRed (Kanto).