You cannot get all 3 Starter Pokemon (Torchic, Mudkip and Treecko) in Pokemon Emerald without trading for 2 of them.
You cannot get all 3 Starter Pokemon in Pokemon Emerald without trading for the other 2.
you can migrate him from emerald or sapphire.
All if you have a gameshark
In Pokemon Emerald, Eevee and Poliwhirl can only be obtained via trading...
You migrate it from Ruby, Sapphire or Emerald. You get it from those games via Mystery Gift event.
beat the battle frontier!