Originally Posted by
Sephiroth
No, the real question is why don't you have Gyarados when fighting Misty. You can get a Magikarp early and using it in random battles, the Moon Mountain and North of Cerulean City results in it evolving early enough making the Gym Battle easy enough and giving you a Pokémon you can use for the rest of the game. Gyarados is not even threatened by Lt. Surge because Lt. Surge is beaten by a single Dugtrio.
I haven't caught a Gyarados because I caught a Pikachu. Pikachu is not threatened by Misty's or Surge's gyms at all. Gyarados learns Bite at level 20, which makes it outclassed in Generation I by
Squirtle. I don't even need to catch a Dugtrio. Gyarados' Special is still really bad in Gen I, so the best move that it learns is Strength, not counting Hyper Beam.
Even further than that, you don't even mention that instead of Trainer-Fly to get Gengar with Night Shade, you can Trainer-Fly yourself a level 100 Gyarados with Dragon Rage in Mt. Moon. So instead of getting the useful Gyarados, you got the useless Gyarados.
Have you
played this game before?
I A M S U R R O U N D E D B Y C A S U A L B O Y S , B O Y S
No reasonable person could ever be expected to know any of this.