There is only one TM38 Fire Blast. You receive it from Blaine after beating the Cinnabar Island Gym.
Yes, it learns Fire Spin, and you can also teach it Flamethrower and Fire Blast.
Gyarados is always a water/flying type, you can teach it fire type moves though.
There is no strongest pokemon. The best you can do is have a balanced team with a wide variety of moves. But it could be groudon. If you teach it solarbeam, and strong fire, rock, and earth moves. it will pwn.
The best moves for Charizard is Blast Burn, Flamethrower, Fire Blast, and Heatwave. Don't teach Charizard Overheat. Overheat is strong but your sp. atk will fell.
Fire type moves
Of course this depends on your pokemon. My team's best moves are fire blast, flamethrower, surf, hydro cannon, dragon claw, dragon breath, fly, and earthquake.
Fire type Pokemon or fire type moves beat electric Pokemon.
You teach a water Pokemon mimic and when a fire Pokemon shoots a fire attack your Pokemon will shoot it to!!
It depends... a Fire Pokemon learns a lot of burning moves, the water pokemons, water moves...
Whether or not a Pokemon is the best, is merely a matter of opinion. In this case, ask anyone what fire Pokemon is the best and each person will tell you a different Pokemon. Any Pokemon can be the best, if you train it well and give it powerful and strategic moves. For instance, you can level a Charmander, to lvl 100 without evolving it, and if you teach it good moves, it could essentially be the best. Likewise, if you have an Entei, and level it up and teach it good moves, it could be the best. All you have to do is choose which Pokemon you want and train it well, and it will be the best.
Ground type moves, rock type moves and water type moves are super-effective against fire type pokemon.
It depends on what poke it is, go in to the house beside the lake in pastoria city. Talk to the man and he will offer to teach your Pokemon an old move for a heart scale. one of the old moves might be fire fang, it worked for my arcainine.