Really, a lot of the early challenges in Pokémon Red and Blue depend on which starter you pick. If you start with Charmander, Brock and Misty will be real tough because they weaken your first friend, but if you chose Bulbasaur, you’re sitting real pretty for those early gyms. However, there’s one gym leader who is an inherent challenge to most players because her typing is broadly overpowered in these first games: Sabrina. The psychic-type trainer’s team of mind-bending, telekinetic weirdos got a multi-episode arc in the anime because of how busted she was in Red and Blue’s meta.
The psychic type has only two weaknesses in these games: ghost and bug-type attacks. Ghost Pokémon are exclusively found in Lavender Town’s Pokémon Tower and only consist of the Gengar line in the first games, and bug-type Pokémon are notoriously weak. So your options for fighting Sabrina are pretty limited. Even if you had more options, it wouldn’t change the fact that Sabrina’s team is not fucking around. Her Kadabra, Mr. Mime, and Alakazam are all pretty tough, and each has good offensive, defensive, and status capabilities in their arsenal. The psychic typing was so busted back in the day, Game Freak had to introduce dark-type Pokémon in Gold and Silver just to balance things out.
Before we move on, let’s give an honorable mention to Brock in Pokémon Yellow. Because you’re required to use Pikachu as your starter in that game, you’re left with almost no options as Pikachu’s electric attacks don’t affect Brock’s team. The only option you have is to power through it with less than effective moves, or overlevel a Nidoran to the point of learning Double Kick. It’s one of the moments when it becomes clear how the game was clearly built around the original grass, fire, and water-type starters, and how removing those options from the early game could change everything, even with Brock’s team being a few levels lower than it was in Red and Blue.