Battle strong, wild Pokemon to increase the amount of experience points you earn per battle. Go to the Cerulean Cave, which is north of Cerulean City in Kanto, and Mount Silver, which is located west of the Pokemon League Reception Gate; the strongest Pokemon lurk here. In the Cerulean Cave, you will find wild Pokemon reaching up to level 40. On Mount Silver, the wild Pokemon will be closer to level 50.
In “Pokemon HeartGold,” whenever your Pokemon gains a level, it will receive a boost in battle attributes, as well as a chance to learn a new attack. However, the stronger your Pokemon, the more experience points it will need to collect to gain a level. There are several items and training strategies you can incorporate to boost your Pokemon’s level in a short amount of time.
Battle strong rival trainers to earn high amounts of experience points for your Pokemon. Seek out the regional Gym Leaders and challenge them to rematches. To request a rematch, obtain the phone numbers of the Gym Leaders by finding them in various locations around the regions.
Equip your Pokemon with the Exp. Share item. The Exp. Share allows the holder to take a share of experience points earned by other Pokemon on your team. Acquire the Exp. Share by taking the Red Scale to Mr. Pokemon on Route 30 in Johto.
Feed your Pokemon Rare Candies. A Rare Candy will instantly boost your Pokemon by one level. Explore every corner of the map to find additional Rare Candies, as they appear in a few places throughout the game. Use the Dowsing MCHN application on your PokeGear; it will reveal hidden Rare Candies in the Tin Tower, Mount Mortar, the Whirl Islands and Cinnabar Island.