Things You'll Need
Instructions
Plug one end of the Game Boy Advance link cable into the link cable port on the top of your Game Boy Advance system. Plug the opposite end of the link cable into the link cable port on the other Game Boy Advance system.
Turn on both systems with the necessary "Pokemon" game cartridges inserted, and load your "Pokemon" save files.
Walk into the Pokemon Center. Pokemon Centers can be found in every major town in the game. Do the same on the second system.
Walk upstairs and speak to the woman guarding the middle door. When prompted to save your game, do so. Do the same on the second system.
Confirm that you want to create a system link with another player, and proceed through the middle door. Do the same on the second system.
Walk to one side of the console in the center of the room and press the "A" button. Highlight the Pokemon that you want to trade for Suicune, and select the "Trade" option. Do the same on the second system, but select Suicune as the Pokemon to be traded.
Confirm the trade. Once the trade process is finished, Suicune will appear in your Pokemon party.