Indigo Plateau (Japanese: セキエイこうげん Sekiei Plateau) serves as the capital for the Pokémon League. It is the final destination for Pokémon Trainers competing in Indigo or Johto League competitions against the Elite Four. This is where the powerful Elite Four battle against Trainers in a final showdown of becoming a master Pokémon Trainer, who may be challenged after defeating all eight Gym Leaders of either respective region. In the anime, it is also the location of the Indigo Plateau Conference, Kanto Grand Festival and the Pokémon League Village.
Indigo Plateau is located just north of Victory Road and Route 23, and east of Mt. Silver. In Generation I and III, the only way to reach Indigo Plateau is by going through Route 23; however, in Generation II and IV, Indigo Plateau is reached by going through Route 26. In order to reach Indigo Plateau by foot, Trainers must venture through Victory Road, a lengthy cave acting as a final test for Trainers.
The Elite Four must be battled consecutively, with breaks to the Pokémon Center prohibited. Trainers are unable to go back or return to previous rooms. The only way to open the door and progress through each room is to defeat the Elite Four member of that room. Each member of the Elite Four is stronger than the previous member, and like Gym Leaders, each specialize in a different type.
in BLUE GENESIS the system of League was similar to B/W/B2/W2/X/Y League : the Elite Four may be challenged in any order the player wishes.Elite Fours music in BLUE GENESIS ==>
Sara ==> FAIRY
Agatha==> GHOST (although' his Pokemon are all POISON Type)