In "Pokemon FireRed," Gyarados is a rare Water- and Flying-type Pokemon that is known for its violent, aggressive nature. It evolves from the vulnerable and weak Magikarp at level 20. Gyarados has extremely high attack statistics and can learn powerful moves such as Hydro Pump and Hyper Beam. The only way to encounter and catch a high-level Gyarados in the wild is to fish with a Super Rod.
Travel to Lavender Town and exit through the southern gate to reach Route 12.
Head south on Route 12 until you reach a long bridge. Walk down the bridge and enter the house on the pier.
Speak to the fisherman inside the house and answer "Yes" to his question. He will give you a Super Rod.
Exit the house and walk onto the pier. Face the water and press "Start" to open the in-game menu. Select "Super Rod" from your Key Items bag.
Fish with your Super Rod for a Gyarados. There is a 15 per cent chance of encountering a Gyarados by fishing with your Super Rod. If you encounter other wild Pokemon, either defeat them in battle for experience points or run away.
Battle Gyarados and strike it with effective Electric-type attacks to weaken it until its hit points are in the critical red zone. The Gyarados that you encounter while fishing with your Super Rod are at relatively high-levels, between levels 30 and 40.
Throw an Ultra Ball at Gyarados to catch it. If it breaks free, continue throwing Ultra Balls at it until you capture it.