It is impossible to get all three starter Pokemon in one game without trading, unless you are willing to use an Action Replay.
Simple. You can't.
You cannot get all 3 Starter Pokemon in Pokemon Emerald without trading for the other 2.
There is no other way.
The only other way is to cheat.
You cannot without a cheating device such as the Action Replay. Sorry.
you don't. in soviet russia Pokemon trade you
there is no other way unless you either trade or go to the global trading center in jubilife
action replay or trading
Get a Action Replay DS or trading.
You'll need an Action Replay for that, or trading restarting trading restating trading back
You cannot possibly get all three. Only one without a hack.
trading with people who also own a copy of Pokemon
trade with friends and/or wifi trading