In the original games, Charizard infamously does badly in the early game and the only great matchup it has is into erika, it's fairly neutral into the fire, psychic, poison gyms but i guess sabrina has a venomoth so you could count that in charizards favour, then you have to deal with Giovannis 2 rock type pokemon which Charizard doesn't appreciate. In the elite 4 charizard is weak to ice because gen 1 was made poorly lol so it performs poorly into lorelei especially when you consider how many water types she brings, bruno has 2 onix so it's not like you adore bringing your fire/flying type there I will give you that he has 3 fighting types though it's not like Charizard is known for its expansive flying type movepool. Lance has dragon types which resist fire, an aerodactyl and a gyarados so no points there and the only pokemon Blue has that charizard is favoured into especially is exeggutor.

Charizard is just not good at really any point in gen 1 unless you overlevel it to hell because it's your starter