No Random Encounters in Grass
As you maneuver your character through grassy areas, he will come under attack by wild Pokémon. This serves as an opportunity to capture these creatures to add to your collection; however, it can also become annoying if you are trying to quickly complete a task. Teaching your Pokémon how to use the HM Cut ability will allow them to remove the grassy areas from your path. The selected Pokémon will cut down all the grass in the area, which will allow you to safely pass through. Use this technique if you are trying to quickly reach the next section of the game.
The Box Trick
The box trick is a secret that allows you to quickly boost your Pokémon's stats and power. Select any of your available Pokémon and deposit it into one of the PC boxes that you find throughout the game. Most are located in the various cities you travel to. Immediately withdraw the Pokémon from the same PC box. The game automatically recalculates all of the Pokémon's statistics and even gives it a slight boost in some areas. Continue to place your Pokémon and withdraw them from the box to increase their strength without battling against another Pokémon.
Evolution Trick
When Pokémon become strong enough, they will evolve into a more powerful version of a creature. You can use this trick to cause that evolution to occur quicker. Place the Pokémon you want to force to evolve into the first slot of your belt. Then put one of the following Pokémon into the second slot of your belt: Exeggutor, Missingno, Growlithe, Onix and Psyduck. Once you have your belt arranged in this fashion, use the Pokémon in your first slot in a battle to cause it to gain a level. Once it gains the next experience level, it will automatically evolve into the next creature type.
Game Shark Codes
Players can use a Game Shark device to unlock many different codes to use while playing "Pokémon." For example, to unlock the secret Pokémon Mew, a player must use the Game Shark because he is not available in the game through any other manner. The Game Shark manual provides a listing of the available codes, including "Pokémon."