To trade between FR/LG to Emerald, Coloseum, Ruby, Sapphire, or XD, you first need to beat the Elite Four. Then, after the credits, you will be in Pallet Town. Go and talk to Professor Oak. He will give you a National Dex. Then go to One Island. Talk to Celio, and he will ask you to help him find two stones. Head to Mt. Ember. Talk to the team Rocket members to the right of the entrance. Battle and win, then go inside the cave. Follow the cave's winding tunnels, and you will see a red colored stone eventually. (sorry i don't know the direct route) Then, head back to the One Island Pokemon Center, and give the stone to Celio. He will then ask for the second stone, and give you his Rainbow Pass, allowing you to travel to all seven islands. First, head off to Six Island. Go south, and you will find a closed up cave. Read the cave door by pressing A, then have a Pokemon use Cut on the door. After, go inside, and go down the ladder. Then, you will have to fall down the holes in a certain order according to the floor. IF you mess up, then you will start over. I think the order is Up, Left, Down, Right, but I'm not too sure. You will then encounter a blue stone. Go and grab it, but it will be stolen. Now leave the cave (Dotted Hole) and head for Five Island. Go south, to a building. Press A on the door, and your character will put some codes in. You then should be in the Rocket Warehouse. To get through this warehouse and to get the stone back, read the big post I left on page 15 of this board. Once you have won the stone back, bring it to Celio. Then, you will be able to trade to any game. (In Emerald, you must defeat the Elite Four before trading to anything but Ruby and Sapphire.)