you have to have a game link cable and another Pokemon emerald
You cannot get all 3 Starter Pokemon (Torchic, Mudkip and Treecko) in Pokemon Emerald without trading for 2 of them.
cheat
No. You can, however, get one of the Johto starters from Professor Birch once you have registered all 200 Pokémon in the Hoenn Dex.
No, not without trading from another black or white
The only 2 ways to get johto starters is to see all Pokemon in emerald, and beat mt.battle in Pokemon XD and then send them to ur gameboy adv.
you have to have a game link cable and another Pokemon emerald
two words: YOU HACK
It is not possible to get all three starters in Pokemon LeafGreen without trading. This was an intended mechanic to encourage interaction between players.
You cannot get all 3 Starter Pokemon (Torchic, Mudkip and Treecko) in Pokemon Emerald without trading for 2 of them.
That's impossible.
cheat
No, you can only get all starters without trading in Pokemon yellow, but Leaf Green is a newer version of Pokemon green, so it's impossible.
No. You can, however, get one of the Johto starters from Professor Birch once you have registered all 200 Pokémon in the Hoenn Dex.
a bunch
No, not without trading from another black or white
You cannot get all 3 Starter Pokemon in Pokemon Emerald without trading for the other 2.