Several methods are available through the C-Gear which is a key itme you receive early on in the game. Using wireless internet connection it's possible to trade with players in any Pokemon Center on the top floor. For players without internet connection there's also IR connection (infrared). IR is for people to connect with each other that are close by rather than long distanced.
There's also a Dream World and Entralink where you can drop off pokemon for trade.
you need 2 ds's to go to the trade room in both and connect
Well, first and only you have to DIEDIEDIE
To trade Pokemon go to the poke center and go up stairs into the union room.
go to the union room with a friend
go in the pokemon center, in the middle section there is a lady. talk to her and go inside. a another person will need to be there to trade pokemon
Go to the Union Room.
First... You Have To Get To A Pokemon Center. Go Up Stairs And Speak To One Of BattleLadys At the Top. You Have To Speak To The One In The Middle And You Will Get Shown To The Union Room. When Your In The With One Of Your Friends Speak To Them And You Will Be Able To Trade Or Battle(:Hope This Helped(:
Go to the union room on the second floor of the pokemon center, or trade over wifi.
you have to beat the game to trade for Pokemon outside the game but if you've already beat the game just go to the top floor of the pokecenter
in order to trade, you and you're friend both have to go to the Pokemon center and go up the stairs. there will be a symbol on the floor(a pokeball with dots around it) in front of a lady. both talk to her, and you will save and go into the union room. talk to your friend and say trade. make sure your friend accepts. then trade.
there is a code. I forgot it but you can trade legendary Pokemon at the union room. you go up the stairs to the second room in the healing place. you keep saying yes and then you go in. then talk to him and press trade the trade
go to the union room and trade