There is more to it than this. First, apply Doesn'tKnowHowToPlay's patch for either Fire Red or Emerald. Then, open the ROM in Pokémon Game Editor (PGE). Go to the Attack Editor internal program, and manually switch every attack's category to the proper one, since the patch changes everything to physical for some reason. You may also want to change the casing of the words so that "FLAMETHROWER" becomes "Flamethrower", and so on.