Buy it at the game corner
Go to Vemillion City and Route 130 and you will find it there.
TM50.
Substitute
Charizard can learn TM50- Overheat.
TM11(Sunny Day) TM35(Flamethrower) TM38(Fire Blast) TM50(Overheat)
The only way to teach Flareon Overheat is use TM50 Overheat OR use action replay.
Blaziken learns Overheat from TM50-Overheatwhich you can get from defeating Flannery the 5th Gym Leader.Your's Truly- yehthatisme
You get Overheat (TM50) from Blaine in the Seafoam Islands. He is a Gym leader and only gives it to you after you beat him. he is a fire-type gym leader.
To get the TM, go to Stark Mountain and get to a part where you have to push a boulder left. At the end, you go down and get past the trainers. The Pokeball contains TM50 Overheat.
Level 32: Fire Fang Level 48: Flamethrower TM11: Sunny Day TM35: Flamethrower TM38: Fire Blast TM50: Overheat TM61: Will-O-Wisp
The fourth gym in pokemon emerald is a fire gym in lavadrige city led by Flannery. She has a numel, slugma, camerupt and a torkoal. If you beat her she will give you a TM50 overheat. So I suggest that you brign water pokemon with you as a counter.
The left window offers: Abra, Vulpix, and Wigglytuff. The middle window offers: Scyther, Pinsir, and Porygon. The right window offers: TM23 Dragon Rage, TM15 Hyper Beam, and TM50 Substitue