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

Raichu flying mechanics by warden006 -- Fur Affinity [dot] net

Flying type Raichu

OPERATIONiDROID

Raichu Pokémon Amino

What Pokemon That Can Learn Fly? (Move)

FireRed hack: - Pokémon Gaia Version

The dialogue in Pokémon Gaia is so self aware, I love it. I haven't laughed this hard at a Pokémon game in ages. : r/PokemonROMhacks

FireRed hack: - Pokémon Gaia Version

Raichu Pokédex

FireRed hack: - Pokémon Gaia Version

vp/ - Pokémon » Thread #40059529

FireRed hack: - Pokémon Gaia Version