Pokemon Yellow Gym Leaders
Like all Pokemon Games, there are eight Pokemon Gyms also in Pokemon Yellow that you must the player must defeat in order to face the Pokemon League. Unlike Pokemon Red and Blue, the Gym Leaders have Pokemon Teams which much higher levels that relate more closely to the Anime Series of Pokemon.
Pokemon Red Gym Leaders:
#1) Pewter City Gym:
The first gym is found in Pewter City. The Gym Leader is Brock, a Rock-Type Pokemon User.
Brock's Pokemon: Level 10 Geodude & Level 12 Onix
After you defeat Brock, you'll receive the Boulder Badge and TM34 (Bide). You will also be allowed to use HM05 (Flash) outside of battle.
#2) Cerulean City Gym:
The second gym is found in Cerulean City. The Gym Leader is Misty, a Water-Type Pokemon User.
Misty's Pokemon: Level 18 Staryu & Level 21 Starmie
After you defeat Misty, you'll receive the Cascade Badge and TM11 (Bubblebeam). You will also be allowed to use HM01 (Cut) outside of battle.
#3) Vermilion City Gym:
The third gym is found in Vermillion City. The Gym Leader is Lt.Surge, an Electric-Type Pokemon User.
Lt.Surge's Pokemon: Level 28 Raichu
After you defeat Lt.Surge, you'll receive the Thunder Badge and TM24 (Thunderbolt). You will also be alllowed to use HM02 (Fly) outside of battle.
#4) Celadon City Gym:
The fourth gym is found in Celadon City. The Gym Leader is Erika, a Grass-Type Pokemon User.
Erika's Pokemon: Level 30 Tangela, Level 32 Weepinbell & Level 32 Gloom
After you defeat Erika, you'll receive the Rainbow Badge and TM21 (Mega Drain). You will also be allowed to use HM04 (Strength) outside of battle.
#5) Fuchsia City Gym:
The fifth gym is found in Fuchsia City. The Gym Leader is Koga, a Poison-Type Pokemon User.
Koga's Pokemon: Level 44 Venonat, Level 46 Venonat, Level 48 Venonat & Level 50 Venomoth
After you defeat Koga, you'll receive the Soul Badge and TM06 (Toxic). You will also be allowed to use HM03 (Surf) outside of battle.
#6) Saffron City Gym:
The sixth gym is found in Saffron City. The Gym Leader is Sabrina, a Psychic-Type Pokemon User.
Sabrina's Pokemon: Level 50 Abra, Level 50 Kadabra & Level 50 Alakazam.
After you defeat Sabrina, you'll receive the Marsh Badge and TM46 (Psywave).
#7) Cinnabar Island Gym:
The seventh gym is found on Cinnabar Island. The Gym Leader is Blaine, a Fire-Type Pokemon User.
Blaine's Pokemon: Level 48 Ninetales, Level 50 Rapidash & Level 54 Arcanine
After you defeat Blaine, you'll receive the Volcano Badge and TM38 (Fire Blast)
#8) Viridian City Gym:
The eighth and final gym is found in Viridian City. The Gym Leader is Giovanni (Team Rocket Boss), a Ground-Type Pokemon User.
Giovanni's Pokemon: Level 50 Dugtrio, Level 53 Nidoqueen, Level 53 Persian, Level 55 Nidoking & Level 55 Rhydon.
After you defeat Giovanni, you'll receive the Earth Badge and TM27 (Fissure).
After you have defeated all eight Kanto Gym Leaders, as expected, you can battle the Kanto Pokemon League (Elite Four / Champion).