* Battle high-level Pokémon. The higher the level of the Pokémon you battle, the more experience points your Pokémon will gain.
* Use EXP. Share. EXP. Share is a held item that allows all of your Pokémon in battle to gain experience points, even if they don't participate in the battle.
* Use Rare Candies. Rare Candies are items that can be used to instantly level up your Pokémon. They can be found in the wild, or they can be purchased from the Game Freak office in Celadon City.
* Complete side quests. Some side quests in Pokémon SoulSilver reward you with experience points. For example, completing the Pokéathlon Dome quests will earn you experience points for your Pokémon.