The game's influence can also be seen in the competitive Pokémon scene. Fire Red was one of the first games to introduce the concept of competitive battling, with players competing against each other using their Pokémon teams.
Squirrels do not exist natively in Fire Red . The closest: 1636 Pokemon Fire Red - U-- Squirrels
However, if you’re asking what that specific filename refers to: The game's influence can also be seen in
The Gold Standard: Why "1636 Fire Red Squirrels" is the King of ROM Hacking 1636 Pokemon Fire Red - U-- Squirrels
Help you find a (like UniPatcher or NUPS) to apply a mod to your file