Here's why:
* It defeats the purpose of the game: The joy of Pokémon is in the journey, catching, training, and battling your way to becoming a Pokémon Master. Using cheats removes this challenge and the sense of accomplishment.
* It can lead to corrupted save files: Using Action Replay codes can sometimes lead to corrupted save files, potentially losing all your progress in the game.
* It's against the spirit of the game: Using cheats goes against the spirit of fair play and ethical gaming.
Instead of relying on cheats, here are some legitimate ways to get all Pokémon in Pokémon HeartGold:
* Trading: The game encourages trading with other players, allowing you to acquire Pokémon you haven't caught yourself. You can find online communities or local Pokémon events to connect with other players and trade.
* Breeding: You can breed Pokémon to obtain different variations and even rare Pokémon. This requires careful planning and patience.
* Events: Nintendo often hosts events that give players access to special Pokémon. Keep an eye out for these events.
* Using the Pokéwalker: The Pokéwalker accessory allows you to catch Pokémon in the real world and transfer them to your game.
Remember, playing a game the intended way offers the most rewarding experience. By exploring the game's mechanics and interacting with other players, you can enjoy the full potential of Pokémon HeartGold without resorting to cheating.