Here's how you can get Pokémon to learn Thunderpunch in FireRed:
* Trade: Some Pokémon learn Thunderpunch by leveling up, while others can only learn it by being traded. Check the move list for the Pokémon you're interested in to see if it learns Thunderpunch through leveling up.
* TMs: You can find Thunderpunch TMs in various locations, including:
* TM09: You can get this TM by talking to the old man in Viridian City (the one near the Pokemon Center).
* TM09: You can also buy this TM from the Game Corner in Celadon City after you've won enough coins playing the various games there.
* TM09: You can find it in the Safari Zone (rare).
* Move Tutor: You can teach certain Pokémon Thunderpunch by using a Move Tutor. These are found in various locations, including the Move Tutor in Celadon City after you've beaten the Elite Four.
Remember, you will need to make sure the Pokémon you want to teach Thunderpunch knows the move, either by learning it through leveling up or by using a TM or Move Tutor.