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In Red and Blue, there are no Pokemon you can catch between Route 1 and Pewter City that can handle Brock. Rattata can't do any SE damage, Pidgey and the bug Pokemon die to Rock attacks, and Pikachu is completely useless. If you chose Bulbasaur or Squirtle, you were fine. If you chose Charmander, that meant you had to do a lot of miserable grinding before you could challenge him.
In Yellow, they made some changes. This includes being able to catch Mankey on Route 22, having Nidoran available early on and learning Double Kick at level 12, and having Butterfree learn both Confusion and Poison Powder at lower levels than before. In FRLG, they didn't change a whole lot from Yellow, except that Charmander now learned Metal Claw early on, so even if you started with it, you had a chance.
People keep imagining that LGPE fucked over difficulty because they ask you to show a Water or Grass type Pokemon before you're allowed to participate in the gym. It's literally just asking you to prove you know your type matchups, so if for some absurd reason you get stuck, you can know it's entirely your own damn fault.
Quit screaming and whining about "casualization". They're fixing a two decade old mistake, the same shit they've done EVERY TIME THEY REVISITED KANTO.