Whether it's the games or the anime, the heroes of Pokémon are ranked not by the number of pocket monsters they carry with them or the starter they left home with, but by the Gym Badges they earn. Gyms are a staple of the Pokémon universe. It's where trainers come to test their skills against other trainers specifically qualified to battle. Victory means walking away with a badge. Eight badges grant you the privilege to battle the Elite Four of that region.
But not all gyms are made equally, nor are all gyms equal to their counterpart in other mediums. The anime adaptation draws from the games, sure, but some of the easier gyms in the games become insurmountable challenges in the anime series. To answer which Pokémon Gym Leaders are the strongest requires a level-headed study of game mechanics (and a nerdy knowledge of anime epicness).
10. (Games) Whitney: Goldenrod City
Many gamers are well-aware of Whitney, the Goldenrod City Gym Leader who specialized in normal types. From the outside, Whitney seems like a fairly unassuming, standard Pokémon trainer. She has just two Pokémon: a level 17 Clefairy and level 19 Miltank. At this stage of the game, this may seem low-leveled. And you may feel confident, pushing past her Clefairy without trouble.
But then you face Whitney's Miltank.
Many young Pokémon trainers remember with post-trauma flashbacks the first time Whitney's Miltank whipped out their entire team with the move Rollout, a move that consistently grows stronger with each subsequent use. With Miltank's high defensive stats, good luck inflicting any damage on her before that move flattens you. Oh, and just when the Pokémon's HP gets low, and JUST when you think you have this Gym Leader beat, the Miltank has Milk Drink; a move that restores lost HP!
It's telling that many gamers have an easier time beating Whitney in Pokémon HeartGold and SoulSilver's rematch rounds than they did the first time they confronted the Gym Leader.
9. (Anime) Giovanni: Viridian City
The Giovanni that appears throughout the Pokémon games is tough, but he has NOTHING on the head of Team Rocket in the anime. It's almost unfair comparing the two, especially in the early arcs of the series. Giovanni is the intimidating leader of Team Rocket. He's also the only Gym Leader in the first game to have a balanced team of Pokémon, although he primarily focuses on Ground and Poison Pokémon.
That's all well and good, however, game Giovanni, despite being the final Gym Leader, has NOTHING on anime Giovanni. He who commands a criminal empire of thousands with the sheer fear of his presence alone.
But if anyone had any doubts about Giovanni's power as a Pokémon Gym Leader, those doubts were squashed when we saw him fight Gary. Gary, up until now, was always Ash's superior, four steps ahead of him. And yet, in a two-on-one match-up, Giovanni crushed Gary, his team, and all his pride. All thanks to the Strongest Pokemon of All: Mewtwo.
While Mewtwo did escape Giovanni's clutches, the Gym Leader actually tracked down Mewtwo and managed to almost break the world's strongest Pokémon to his will. Anyone who can lay claim to that sort of power deserves to be ranked among the most powerful Pokémon Gym Leaders around.
8. (Games) Brawly: Dewford Town
Fighting-type Pokémon are often discounted. Much like Normal-types, Pokémon games rarely give them any special qualities that make them truly stand out. But the Hoenn Region's Dewford Town is home to the Gym Leader Brawly. This Kanto-born leader only has two Pokémon (again, like Whitney). But his are fighting-types. And they too have a killer move: Bulk Up.
Bulk Up dramatically boosts a Pokemon's Attack and Defense stats, making it harder to hurt them as they hit you harder than ever before. This makes fighting Brawly incredibly difficult. Pokémon on your team that primarily use Attack-stat moves are in for some trouble with that defense, and while Special Attack-centric Pokémon have a better shot at taking down this Gym Leader, his powerful Pokémon are more than likely gonna pulverize you long before you can inflict a second move. You better have a ton of Potions and Revives before taking on this Gym Leader.
7. (Anime) Roxie: Virbank City
It was once said that rock-and-roll could poison and corrode the youth of America. If that's true, then this rock-and-rolling Gym Leader must be pretty poisoned, seeing as this powerful Pokémon trainer specializes in Poison-types.
While Roxie in the games is no slouch, Roxie in the anime is notorious for only using three Pokémon against a challenging trainer's full team of six. At the end of the Unova League, Ash has a pretty powerful team of six Pokémon, including his lifelong companion Pikachu. So you would think that in a six-on-three fight, Ash would have this Pokémon battle in the bag.
Ash only beats Roxie because the powerful Gym Leader decides to let Ash heal his Pokémon. If not for that, it would've been curtains for the trainer from Pallet Town.
6. (Games) Blue/Green: Viridian City
Giovanni isn't the only Gym Leader of Viridian City. In Pokémon Gold and Silver and its remakes, Giovanni is on the run, leaving the Viridian City Gym empty for a new Leader to take command. And the trainer that takes claim is none other than your rival from the previous games and former Elite Four Champion, Blue. It could also be Green, depending on which country you're playing the game in.
Blue's team is incredibly high leveled, but what makes this Gym Leader such a challenge is that he has no primary type of Pokémon. Instead, he uses a balanced team that will test your mantle. You'll need to strategically approach each new Pokémon as if it's a new Gym Fight, careful to match type and skill set against the right opposition. And if that's not enough, the rematch goes even FURTHER into levels of absurdity.
Sure, Blue is only the second toughest opponent in Pokémon Gold and Silver (second only to Red), but even that makes him among the most powerful around. Period.
5. (Anime) Volkner: Sunyshore City
The Sinnoh region may not be as fondly remembered as Kanto or Johto, but its final and most powerful Gym Leader, Volkner, may take the cake for being the most intimidating Leaders around. Best friends and rivals with an Elite Four member (Flint), Volkner basically is on an extended sabbatical from training until he watches Ash battle his rival. Only then does he decide to return to Gym Leading, challenging Ash to a battle that shocks him to his core.
Volkner specializes in Electric-type Pokémon so powerful that, even after an extended period of not battling, he basically has Ash beat. It's only thanks to Ash's Infernape having a sudden Dragonball Z-esque power-up that Ash manages to overpower and beat Volkner. Volkner is so powerful the writers had to break the logic of Ash's own team in order to justify the hero beating this Gym Leader. And keep in mind, this is after a prolonged break from battling. This is Volkner out-of-shape, and Ash—one of the strongest characters in the series—still almost lost!
That's quite a feat!
4. (Games) Clair: Blackthorn City
All great heroes, to prove their worth, must overcome at the end of their journey. Johto's final Gym Leader Clair may not be a dragon herself, but she reigns over them as queen.
Dragon-type Pokémon—at this stage of Pokémon's history—had few weaknesses. And while Clair's team is not completely dragon-focused, it is her specialty. With few type-disadvantages, Clair was a challenge for most Pokémon trainers hoping to reach the Johto Elite Four already.
It isn't enough that you could face Clair a second time, but you could later challenge the Gym Leader for a third match. However, this time Clair stood side-by-side with the Johto's Elite Four Champion, Lance. Two of the most powerful Pokémon trainers in the whole game, side-by-side, fight you and your rival. With a level 75 Dragonite, few players were prepared for Clair's might in this be-all, end-all challenge.
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3. (Anime) Olympia: Anistar City
Olympia isn't simply one of the strongest Pokémon trainers around. She's also just one of the most powerful things in Pokémon, period. With her psychic powers, Olympia foretold of the calamity between Primal Kyogre and Primal Groudon, taking measures to protect those around her. Later, she predicts the dangers of Zygarde, and later still helps defend the world from the villain Lysandre by destroying the "Giant Rock," a pseudo-Zygarde entity of legendary power.
While Ash's battle with Olympia is intense, it pales to her own abilities as a psychic. Being able to predict the future and form strategies accordingly is an incredible talent. Thankfully, Olympia uses her powers for the benefits of mankind rather than to demolish the world of Pokémon.
2. (Games) Sabrina: Saffron City
While the first generation of Pokémon games are fondly remembered, they are not without their game-breaking bugs. One that is least talked about outside of the competitive scene is that Gen 1 Psychic-types had no type disadvantages other than Bug-types. However, most Bug-type moves in Gen 1 did very little damage. This meant Saffron City Gym Leader Sabrina facing a trainer the game itself granted no weaknesses. Facing Sabrina is an endurance test of both patience (her gym requires you to hop from teleportation pad to teleportation pad) and skill. Sabrina's Pokémon all had devastating attacks that did tons and tons of damage.
Oh, and if you watched the anime and thought that you could use a Ghost-Type Pokémon to resist her, guess again! Psychic-type moves were super-effective against Poison-type Pokémon, and all Gen-1 Ghost Pokémon were also Poison-Types.
If you failed, that meant going all the way back to the Pokémon Center, starting the teleportation leap-frog game all over again.
1. (Anime) Sabrina: Saffron City
That's not a mistake. Saffron City's Gym Leader is not only the most powerful Pokémon Gym Leader in the games, but she's also the most powerful Pokémon Gym Leader in the anime. Simply put, Sabrina is unstoppable. She's not a challenge, not a tough battle — she is literally impossible to defeat.
Remember Olympia and her psychic abilities? Sabrina has those, too. Except hers are more terrifying. She leveled a house when she was a child, teleports around, manipulates a creepy doll, and—if she really doesn't like you—can just transform you into a doll. This leaves you forever alive and aware of your state like something out of I Have No Mouth, and I Must Scream.
And we haven't even gotten to her Pokémon yet...
Sabrina and her Kadabra are linked on a psychic level. While Kadabra is powerful already in the anime, this Kadabra can use his psychic powers to throw attacks even stronger right back at his opponent. But let's say you manage to land a lucky hit and hurt Kadabra. Well, it can recover from seemingly any attack, making it literally impossible to defeat.
Sabrina is like something out of a nightmare: ruthless, unstoppable, and nigh-omnipotent.
Good luck beating this Gym Leader and getting your Marsh Badge.