Things You'll Need
Instructions
Find out which Pokemon are available in your game version using an online Pokedex, such as the one at the official Pokemon website. Use the Pokedex as you play to keep track of the Pokemon you have caught.
Play through your first version of the game, defeating your opponents and capturing their Pokemon. Beat the game and save your game.
Go through the game again, fighting random roaming Pokemon. Capture any Pokemon you don't have and let go Pokemon you have already captured.
Repeat the process until you have captured all the Pokemon in the game. Explore out-of-the-way areas, such as caves and northern villages to find rarer Pokemon.
Put in a different version of the game and use your online Pokedex to find Pokemon unique to this version. Fight against trainers and roaming Pokemon to find the unique Pokemon.
Repeat the process with each game version until you have captured every Pokemon.