However, there are other ways to level up your Pokémon in HeartGold:
* Train in the wild: The most common method is to battle wild Pokémon and gain experience points.
* Use Rare Candies: These are rare items that can be found in certain locations or obtained through trading. Each Rare Candy gives your Pokémon a full level.
* Use Exp. Share: This item can be held by one Pokémon in your party, and all Pokémon in your party (except the holder) will receive a percentage of the experience points earned.
* Use the "Exp. All" feature: This is a post-game feature that allows all Pokémon in your party to receive experience points from battles, even if they don't participate directly.
So, while you won't find an Exp. Card in HeartGold, you have several alternative options to level up your Pokémon.