In Pokémon Gold, Silver and Crystal you get to fight 16 gym leaders16 and you can get 16 badges. The first 8 are necessary to be able to participate in the Pokémon League. if you win, you can get from Johto to Kanto and visit the 8 gyms there.
Johto Gym Challenge
1: Violet City Gym, leader: Falkner, uses bird
Pokémon
2: Azelea Town Gym, leader: Bugsy, uses bug Pokémon
3:Goldenrod City Gym, leader: Whitney, uses normal
type Pokémon
4: Ecruteak City Gym, leader: Morty, uses ghost
Pokémon
5: Cianwood City Gym, leader: Chuck, uses fighting
type Pokémon
6: Olivine City Gym, leader: Jasmine, who uses
steel type Pokémon
7: Mahogany Town Gym, leader: Pryce, uses ice
type Pokémon
8: Blackthorn City Gym, leader: Clair, uses dragon
Pokémon
Kanto Gym Challenge
Um, not there yet...