@ kietarr
Charmander don't rock in R/B. Fire was a ok type in R/B, but certainly not the best. Besides, for E4, you just a electricity, water and psychic to win all. Charmander does not have much utility, IMO.
Brock : no
Misty: no
Lt.Surge : ok
Erika : Yes, that's provided if u have flamethower. charmander also dies easily to posion.
Sabrina : ok
Koga: not bad, especially yellow where there are only venomoths and venonats.
Blaine: Yes, if u have earthquake.
Giovanni: not much usefulness.
Lorelei (?): no. it's more like a water trainer than an ice trainer.
Bruno: Can kill fighting type with ease
Agatha: yes with earthquake.
Lance: no
Rival: Not much help.
IMO, squirtle is the best starter in R/B. Surf just kill. and learn ice beam which help greatly for Lance.
my 2 cents
LOL Charizard kicked ass in RB you just had to hold off on evolving Charmeleon until Lv42 (A whole 6 levels) for Flamethrower. It was even more ridiculous if you got it up to 56 before evolving and had Fire Spin (which was pretty much instant win)
Brock didn't have any Rock attacks in RB. I solo'd his Gym with Charmander one game because his pokemon are completely boned if Ember Burns them, and all they can do to respond is Tackle or Bind. Since Bide didn't have priority then, you'd just Growl at them while they were biding making them even more useless.
Misty did kick Charmander's butt though.
Surge was neutral, but if you used mega EXP building Diglett's Cave, you can easily get Charmeleon to Lv 36 for Slash and mop the place up.
Erika's Gym is basically Exp building for Charmeleon.
Sabrina < Slash.
Koga < Flamethrower
Blaine < Slash. EQ is just an unneccesary bonus.
Giovanni is a problem that can be solved by "Starmie used Surf," but Zard himself isn't much help there.
Slash/Flamethrower Charizard was rididulous. Slash basically had 140 Base Power and aside from Victory Road and Giovanni, most rock types couldn't stand up to Flamethrower. Sabrina gets nuked by Slash's 100% CH rate on Zard, which cuts through Barrier and Reflect. (LOL in Yellow where Venomoth gets owned by FT).
Charizard is useful for taking out Lorelei's Jynx, but that's about it. If you had EQ Agatha was mostly a breeze, I think only one of the Gengars had Thunderbolt and Golbat gets 2HKO'd by FT.
Charizard easily beat Hitmonchan and Hitmonlee since Bruno didn't give them RS and they had trash special. LOL Thunderpunch.
Wasn't that useful against Lance because Zard was still weak to Ice Beam, but you could still 2HKO most of his pokemon with Slash. Or just use "Starmie used Ice Beam."
Charizard cleans up Rival's Exeggutor, Pidgeot, Arcanine, and Alakazam fairly well. You don't need an "It's Super Effective" message on every attack in order to beat trainers in-game. Charizard and Starmie can beat the entire game between them, though you may just want to pick up Zapdos at the power Plant to Thunder Lapras into oblivion.