Well, The Thing is that you first have to defeat the tasks for all seven islands that includes retreiving the Sapphire and ruby in Pokemon fire red and leaf green. Also, you need to defeat th elite four in emerald and get the national pokedex. Finally, you should be able to trade.
Pokemon Emerald: Birth Island Pokemon Sapphire: Trade from Pokemon FireRed, LeafGreen, or Emerald. Pokemon Ruby: Trade from Pokemon FireRed, LeafGreen, or Emerald.
There is no emerald to trade between firered and emerald you need wireless adapters.
Trade one from firered to emerald.
trade from emerald.
You trade from Pokemon FireRed/LeafGreen
Trade it from Pokemon Emerald or Pokemon XD.
it's not in emerald,you have to trade from leafgreen or firered
Trade a charmander from firered or leafgreen to emerald.
Trade from FireRed or LeafGreen.
Trade from FireRed/LeafGreen
Trade from FireRed or LeafGreen.
Trade from Firered or Leafgreen.