As in other regions, the Kanto region holds a number of Gyms located throughout the area. In the Generation I games and their remakes there are a total of eight Gyms. In the Pokémon Anime, the main character Ash, battled at eight Gyms as well. However, as seen with several characters' Badges, there were other unidentified Gyms that were not shown.
Pewter City Gym
The Pewter Gym (Japanese: ニビジム Nibi Gym) is the first pokémon gym to battle in the Kanto region. Based on its name, the gym strictly uses -type and -type Pokémon. It's located in Pewter City outside of Viridan Forest. There's a total of two trainers in the gym, Brock, the Leader, and a Jr. Trainer.
Cerulean City Gym
Vermilion City Gym
Celadon City Gym
Fuchsia City GymThe Fuchsia City gym is in Fuchsia City. The leader varies in the games. In Red/Blue/Yellow, Koga is the leader, but in HeartGold and SoulSilver, Janine, Koga's daughter, is the leader. Both focus on the -type. Like the other gyms, this uses a special tactic against the player. The gym leader uses a series of invisible walls to confuse new trainers. In some games, the outlines of the walls can be seen and avoided.
Saffron City GymSaffron City's Gym Leader is Sabrina, who uses -type Pokémon. There are teleporting tiles that the player must use in order to get to the gym leader. During Team Rocket's siege, the gym is locked up and will open after Giovanni is defeated.
Cinnabar Island Gym
The Cinnabar Island Gym leader is Blaine, he gives out the Volcano Badge, he uses -type Pokémon. In Gold, Silver and Crystal, the volcano on Cinnabar Island was destroyed except for the Pokémon Center, so Blaine had to relocate to the Seafoam Islands. In HeartGold and SoulSilver his Gym was redesigned and had trainers.
Viridian City Gym
Viridian City's Gym Leader, in Blue, Red, And Yellow, is, somehow, the Team Rocket leader Giovanni, who uses -type Pokémon. In Heartgold, Soulsilver, Gold, Silver and Crystal versions; the leader is Blue who uses all types of Pokémon.