Instructions
Train your team of Pokemon to level 60, at least.
Buy Potions, Revives and other recovery items at the PokeMart.
Save the game before entering the Elite Four arenas.
Defeat Lorelei's Water Pokemon by using Electric and Grass attacks such as Thunderbolt and Giga Drain. Use Fire or Ghost attacks to defeat Jynx.
Counter Bruno's Fighting Pokemon with Psychic and Flying attacks such as Extrasensory and Drill Peck. Use Water or Grass attacks to defeat his other Pokemon.
Use a swift Pokemon equipped with Psychic attacks to defeat Agatha's team. You can also counter her Ghost Pokemon with Ghost attacks.
Defeat Lance's Gyarados with Electric attacks. Use Ice attacks, such as Blizzard or Ice Beam, to defeat the rest of his team.