Things You'll Need
Instructions
Connect your Game Boy Color to your friend's with the link cable. Turn your Game Boys on and begin playing.
Go to any pokemon center and heal your pokemon, then visit the Cable Club receptionist while in the center. Make sure your friend does the same.
Select the "Trade Center" option in the cable club menu, and make sure your friend does the same. You will now both be transported to the trade center.
Face the table in the trading center and press the "A" button. You will now be able to trade any pokemon in your current party with any pokemon in your friend's party.