>>57988587 (OP)Magneton is a better choice than Manectric, he's the nerdy type guy that did the underground city with magnets and shit. Magneton is no longer a pure Electric type line, has a VERY high Sp.Atk for its generation, a solid bulk given by the typing and defenses despite the average HP, paralysis lets him outspeed and stun, Machop/Makuhita/Meditite line is frail and you aren't expected to have Machamp that early, same for Golem, Golem's line has low HP stats and you don't accurately EV your mons in the playthrough so Sonic Boom hits hard, if by the time Gen 3 had the phys/special move split and any weaker version of Flash Cannon it would be raping even more mons.
Your only solid answers for it were Combusken for quick clear or Marshtomp for bulk and Ground x4 damage rather than Fire or Fighting x2.
Else Shedinja if you knew how to obtain in, and even then it would have worked after 40 turns later of normal and bug type weak attacks and dodging confusion.
The other cheese like for some other game gym leaders is Growl/Leer/TailWhip/MudSlap,StunSpore,SleepPowder etc or Headbutt 30% spam, STAB Normal attacks in early gens until 3/4 were very solid bruteforcing options, especially Gen 3 having early level up Sword Dance Zangoose that could later learn Secret Power/Strength, Return, Brick Break, Shadow Ball and Dig too I believe.