Pokémon Family Species: Gen I (Bulbasaur to Parasect / Venonat to Cloyster / Gastly to Miltank / Magikarp to Mew) | Gen II | Gen III (Treecko to Sharpedo / Wailmer to Deoxys) | Gen IV | Gen V (Victini to Zoroark / Minccino to Genesect) | Gen VI (Chespin to Hawlucha / Dedenne to Volcanion) | Gen VII (Rowlet to Comfey / Oranguru to Melmetal / Ultra Beasts) | Gen VIII (Grookey to Hatterene / Impidimp to Calyrex) | Glitches
Pokémon Human Characters: Protagonists and Rivals (Kanto / Johto / Hoenn / Sinnoh / Unova / Kalos / Alola / Galar) | Professors | Gym Leaders (Kanto / Johto / Hoenn / Sinnoh / Unova / Kalos / Galar) | Trial Captains and Kahunas | Elite Four | Champions
Pokémon Villain Teams: Team Rocket / Team Aqua/Magma / Team Galactic / Team Plasma / Team Flare / Team Skull / Team Yell
Frontier Brains And Other Facility Heads | Trainer Classes | Other NPCs (Aether Foundation / Ultra Recon Squad / Macro Cosmos)
Gyms are Pokémon facilities that serve to test how strong a Pokémon trainer and their Pokémon are. Each gym usually specializes in a single type (though there are exceptions). The highest ranking member of the gym is known as the Gym Leader. They essentially serve as this game's version of boss battles. Defeating them nets the trainer an emblem known as a badge. You need eight of them in order to compete against the Elite Four.
For Alola' equivalent to gym leaders, see Pokémon Trial Captains and Kahunas.
- Adaptation Personality Change: Inverted. The release of Yellow version integrated some of their characteristics from the anime with their game selves, which has influenced some of their ongoing design in repeat appearances, such as Misty's connection to Togepi.
- Asskicking Equals Authority: It's implied that particularly powerful trainers can be appointed Gym Leaders by the Pokémon League, and some of them even turned out to be the authority figure of the place where they locate their Gyms.
- Authority Equals Asskicking: They are universally much more powerful than the other Trainers in their Gyms and usually the strongest trainers in the game up to that point. While their levels vary due to the typically linear nature of the games, in the story, the Gym Leaders are usually considered the most powerful Trainers in the region bar the Elite Four and Champion.
- Badass Adorable: Several Gym Leaders are young children and cute girls, still doesn't change the fact they're among some of the strongest Trainers in the region.
- Badass Family: Many Gym Leaders are related to each other or to powerful Trainers in the same region:
- From Generation II, Janine runs the Fuchsia Gym while her father Koga holds a position in the Elite Four. Falkner also inherited the Violet Gym from his father, and Blackthorn Gym Leader Clair is the cousin of Kanto champion Lance, as well as a descendant of a long line of Dragon-type Trainers.
- From Generation III, Norman is Leader of the Petalburg Gym and also the player character's father. Flannery is Leader of the Lavaridge Gym and her grandfather was a former member of the Hoenn Elite Four. Psychic twin siblings Tate and Liza represent the Mossdeep Gym.
- From Generation IV, Byron and Roark are a father-son pair of miners who represent Canalave Gym and Oreburgh Gym.
- From Generation V, triplets Cilan, Chili, and Cress run the Striaton Gym together. Depending on the version, you'll fight either Drayden or his granddaughter Iris in Opelucid Gym, while in the sequels Drayden is the Opelucid Gym Leader and Iris is the Unova Champion.
- From Generation VI, Korrina is the Shalour Gym Leader and the granddaughter of Gurkinn, an expert on Mega Evolution.
- From Generation VIII, the Gym Leader of Circhester will either be Gordie or his mother Melony depending on the version. Piers, the Gym Leader of Spikemuth, is the older brother of Marnie, one of the player's rivals and a very popular Trainer. In the post-game, Marnie has taken over Piers' position as Spikemuth Gym Leader herself.
- Also in Generation VIII, it's noted the Galar region Psychic gym leaders have always been members of the same family line, and they are also known as powerful psychics themselves. Course since they currently are not among the 8 Major Division gym leaders you don't actually get to meet or fight any of them, except for Avery (who has not yet inherited the position) in the Shield version of Isle of Armor.
- Badass Teacher: Morty states that training young people in the ways of Pokémon battle is also the duty of a Gym Leader. Accordingly, most Gyms are filled with the disciples of the resident Leader, who the player must defeat in order to reach the Leader themselves (a few leaders, such as Jasmine, don't actually have any disciples).
- Early Installment Weirdness:
- In the Spanish translation, Generation I Gym Leaders are the only ones to keep their English names (barring punctual exceptions such as Iris). This extends to the Elite Four and even Professor Oak too, but it's more noticeable in the Leaders not just because there are 8 of them but also because the Kanto Elite Four names aren't particularly English-sounding (Bruno even is a Spanish name).
- Before being Willfully Weak became a uniting trope for Gym Leaders, in the early generations they were sometimes depicted as being truly as weak/strong as they are when you fight them in the story. Falkner in Gen II, for instance, was noted to not even own the Pokémon he used, as they were actually his father's.
- Elemental Powers: Each Gym Leader specializes in a single type of Pokémon. The exception is Blue, since he's a former Champion.
- Floral Theme Naming: In Japanese, all Gym Leaders are named after types of plants. For the Galar Gym Leaders in Gen VIII, the plant theme is largely kept for their English names as well.
- Gender-Equal Ensemble: The Kanto Gym Leaders in Gen II and the remakes, the Sinnoh Gym Leaders, and the Kalos Gym Leaders each consist of 4 female Gym Leaders and 4 male Gym Leaders.
- Graceful Loser: Most Gym Leaders are accepting of their losses, congratulating you on your victory and giving you the earned TM and Badge with well wishes. There are exceptions though, most (in)famously Whitney and Clair.
- Improbable Power Discrepancy: Played With. Despite being hailed (in some continuities) as Pokémon Masters, and having official standing in the Pokémon League, they get beaten by rookie trainers and will be outclassed by wild Pokémon and random trainers you meet later. However, this is because they hold back against you in the name of giving you a fair fight, and are much stronger than their position in the game progession would indicate.
- Poor, Predictable Rock: Initially played straight, and gets progressively downplayed. In the first two generations, it's easy to train a Pokémon that specifically counters the Gym Leader's team, as the Gyms are type-specific. There are a few in-game trades that give you Pokémon specifically designed to counter the Gym (like a Rock-type for the Flying-type Gym). The trope gets downplayed in games after Generation III, where they get more diverse movesets and teams to make them more unpredictable; while still mostly type-specific, they tend to mix in assorted secondary typings to make going after their weaknesses more complicated. Generation V outright averts it by having the first gym directly counterpick your starter.
- Punny Name: Every Gym Leader's name is a pun that relates to their type or is otherwise meaningful in some way. For example, Brock is a Rock-type Trainer, and Misty is a Water-type Trainer. Their names in the Japanese version occasionally combine puns related with their type specialty/traits with the Floral Theme Naming frequently used there. For example, the "take" in "Takeshi" (Brock's Japanese name) not only stands for "岳" (mountain peak), but also "竹" (bamboo).
- Red Baron: Everyone gets a cool title that describes some facet of their specializing type.
- Signature Mon: For the Gym Leaders, this trope works on two levels.
- Each Gym Leader specializes in a certain Type of Pokemon and all the Pokemon in their gym battle (and rematch, when available) are of that type. (Some leaders are indicated — in spinoffs like the original Stadium games or the TCG — to have Pokemon outside their specified Main type).
- Every Gym Leader further has a signature Pokémon (or several) that they're associated with, which tends to be the highest-leveled member of their team and are nearly always sent out last. When fought in the Pokémon World Tournament in Black 2 and White 2, the Gym Leaders always send out their signature Pokémon first.
- Signature Move: Every Gym Leader gives out a TM, near-universally teaching an attacking move of their specialty type. Accordingly, they will have taught that move to most of their Pokémon. Prior to Generation III, the moves these TMs taught could only be learned by TM, giving you one chance to teach the Gym Leader's move to a Pokémon. In Gen III and beyond, several such TM moves became naturally available to many other Pokémon, making the Gym Leader's connection to the specific move weaker, but still present.
- Threshold Guardians: Their primary purpose is to test trainers. Only trainers who beat eight of them in a region are dubbed worthy of challenging the League.
- Willfully Weak: They hold back and/or use weaker teams against challengers who are too low-level to face them at full power, since they exist to test your skill as a trainer, not to stop your journey cold. In games where you can have rematches with them, they show off their full power, where they're all on a roughly equal power level on-par with the Elite Four. This trope becomes more explicit as the generations go on, with Cheren in Gen V noting that he's not allowed to use his main team in gym battles, and in Gen VIII Nessa outright tells the player character that the gym challenge battles are indeed only "test battles" and that it's only after clearing all eight that the Gym Leaders will fight a challenger at full strength.
- Wrestling Doesn't Pay: Many Gym Leaders have secondary jobs/hobbies that are also mentioned in their official titles. Sometimes they relate to their preferred type, sometimes they don't. In some cases, their gyms also double as their non-gym-related place of business. Many of them are just gym leaders, though.