Apparently, in Pokémon Gaia, Raichu can learn Fly : r/PokemonROMhacks

How to Get Fly in Pokémon FireRed: 8 Steps (with Pictures)

How to get HM 02 FLY in Pokemon Fire Red / Leaf Green

HM02 FLY - Pokemon Fire Red / Leaf Green

Pokémon FireRed/LeafGreen Nuzlocke Viability Rankings : r/nuzlocke

How To Get HM 05 Flash in Pokemon FireRed/LeafGreen

COMO PEGAR O HM02 FLY - POKÉMON FIRE RED EXTENDED (HACK ROM)

What Pokemon Can Learn Cut (HM01)

Butterfree generation 3 move learnset (Ruby, Sapphire, FireRed, LeafGreen, Emerald)

Where To Get HM02 Fly in Pokémon FRLG - Guide Strats

Dragonite - Pokemon Red, Blue and Yellow Guide - IGN