Pokémon HeartGold and SoulSilver/Indigo Plateau

Go inside the building. Yes, it's the Pokémon League! Heal your Pokémon at the Pokémon Center inside, and then restock your Full Restores and Revives. Save your game and talk to the man in red in front of the doorway at the top of the stairs. Go on through and begin the Elite Four.

Will
Will is the first Elite Four member you will face. He uses Psychic-type Pokémon.

Koga
Koga uses Poison-type Pokémon.

Bruno
Bruno uses Fighting-type Pokémon.

Karen
Karen uses Dark-type Pokémon.

Lance
Lance is the Champion of the Elite Four. He specializes in Dragon-type Pokémon.