Things You'll Need
Instructions
Power up "Pokemon FireRed" or "Pokemon LeafGreen" and go to Celadon City.
Find Eevee. Take the elevator to the fourth level of Celadon Condominiums and talk to the people on this floor. One of the residents will give you a level 25 Eevee as a gift. Save the game.
Turn on "Pokemon Sapphire" on the other Game Boy Advance and connect both Game Boy Advance systems with the Link Cable.
Go to the Pokemon Center in both titles and go upstairs. Talk to the nurse behind the counter to initiate a trade.
Select Eevee on the "FireRed" or "LeafGreen" game and any Pokemon on the "Sapphire" version and confirm the trade. Eevee will be transferred to "Pokemon Sapphire."