Found south of Sinnoh, Kanto is one of the many regions of the Pokémon world. It was the first region to appear in the Pokémon main series games, and it appeared in future games as well. The design of the area laid the framework for later regions to come. However, many recognize this region for its gym leader battles.
Throughout the history of Pokémon, gym leaders appear in nearly every game. Gym leaders represent different element types, and the gyms they occupy are often themed after that. Part of gyms is oftentimes solving a puzzle or navigating through a maze, yet it's the gym leader battles that cause the most trouble.
9 Erika
Erika runs the serene gym of Celadon City. Before entering the gym, you'll notice a creepy old man is standing outside who exclaims, "Heheh! This GYM is great! It's full of women!" This man is not affiliated with the gym in any way, shape, or form.
By this time in the game, you probably have at least one Pokémon that's super effective against the Grass-type. Erika's Vileplum is undoubtedly her most powerful Pokémon. The Mega Drain move might pose a problem for some players, but overall, it's not the most challenging battle.
8 Misty
As the second gym leader in the first generation of Pokémon, Misty commands a lineup of Water-type Pokémon. After venturing through Mt. Moon, players have thoroughly trained their Pokémon, making them almost ready for the battle. There are numerous trainers around Cerulean City gym, which is why this gym leader isn't that hard. Her Starmie is tough to beat, but it's far from impossible.
7 Lt. Surge
Half of the difficulty of beating Lt. Surge is getting by his gym's traps. If you manage to get by them, Lt. Surge will be waiting with a strong lineup of Pokémon.
He's not the most challenging gym leader in Pokémon history, but he will pose a problem for those without the right element types. The strategy for being Lt. Surge is to catch a Diglett or Dugtrio at the nearby Diglett's Cave. Watch out for his high-level Raichu, which will have the electrifying Thunderbolt move.
6 Blaine
Beating Blaine is as simple as putting out fire with water. If you can grasp this concept, Blaine can be defeated with ease. Players have to surf to get to Cinnabar Island the first time, which means they'll pass numerous Water-types on the way.
Like in most of the Kanto gyms, getting to the gym leader is a little complicated. Players have to answer several skill-testing questions to demonstrate their knowledge of the Pokémon world. If you answer a question incorrectly, you'll have to face a gym trainer. Blaine's most powerful Pokémon is Arcanine.
5 Sabrina
As a trainer with psychic abilities, she shares a deep connection with her Psychic-type Pokémon. Sabrina is the seventh gym leader and one of the most formidable gym leaders in Pokémon history. The Psychic-type has few weaknesses in the first generation of the Pokémon games. Hopefully, you have a Bug-type or Ghost-type Pokémon. For many, exploiting this gym leader's weakness is easier said than done. Sabrina's most powerful Pokémon are Venomoth, Kadabra, and Alakazam.
4 Giovanni
The final gym leader you'll face in Kanto has the highest level Pokémon. By this time in the first generation of the Pokémon mainline games, players will have faced Giovanni multiple times. Steadily, Giovanni has been training and gathering more Pokémon to prepare for this battle. Although Viridian City is the second city in the game, you don't face Giovanni until the end of the game.
Upon beating Giovanni in the Viridian City gym, he will give you TM27 Fissure. Watch out for Pokémon like Rhydon, who have been taught this one-hit KO move.
3 Brock
Pewter City is the third city you'll visit in the Kanto region. Especially for inexperienced trainers who are familiarizing themselves with the Pokémon world, Brock poses a mighty challenge. His high-level Onyx can withstand a great deal of damage while using the move Bide. After a few turns, Bide unleashes a high-damage dealing attack. Especially if you chose Charmander as a starter, this gym is considered one of the most difficult in the Kanto region.
2 Koga
If you managed to get past Koga's maze, which is easy to navigate if you look closely, prepare for one of the game's most difficult gym battles. The Poison-type is irksome with a status effect. A poisoned Pokémon loses health at an ever-increasing pace. You'll need a robust inventory of potions and antidotes to get through this battle. Muk uses the Minimize move in combination with moves like Sludge and Poison Gas. Defeat Muk swiftly or expect it to be a frustratingly long battle.
1 Blue
While he didn't appear in the first generation of the Pokémon main series games, Blue is the hardest gym leader in the second generation and its remakes. He has a robust lineup containing Pokémon like Gyrados, Exeggutor, Rhydon, and Alakazam.
This gym leader can be beaten with a diverse lineup of your choosing. If you possess the correct element types to combat this foe, he can be beaten. His Pokémon have been taught moves like Hyper Beam, Psychic, Recover, Earthquake, and Solar Beam. Blue is unquestionably Kanto's most difficult gym leader.