Ok, so.... I don't know when you can trade. I'll give you 2 Ideas. I'll use Japanese names since the English names suck.
1. Have him trade over the neccesary pokes for you and him to have all 3 starters in the beggining if you get to trade early in the game. This takes a long time. I did it with my bro in Fr/Lg. It took an hour. Make sure you have 4 Spare pokemon.. Ex. You get Naetoru and he gets after you're done trading all the pokemon Pochama. You need him to trade you before he gets the pochama:
2 Hikazoru. 1 for you, and 1 for him.
1 Pochama for you.
1 Naetoru for him.
Make sure he has 2 spare pokemon. Trade them back. Release the traded pokemon.
So...
2. If you don't trade early in the game, then you can always do this:
Get 2 seperate starters. Later in the game, trade eggs of the starters. Then, on WiFi, one of you get the 3rd starter that neither of you have. Get it, evolve all the way, and then breed to give the egg to him. Of course, this isn't in the beggining, but trading might be later in the game and you don't want to start over again and again to get half through the game each time, so this might be your best bet.
I hope I helped. If you don't understand anything, PM me. =)
