You don't.
You cannot get all 3 Starter Pokemon in Pokemon Emerald without trading for the other 2.
You cant without action replay
You can't unless you picked it as starter pokemon.
its simply not possible
It is impossible to get all three starter Pokemon in one game without trading, unless you are willing to use an Action Replay.
There is no other way.
Not without trading from another game.
You can get a Cyndaquil without trading only by transfering it from a GBA Pokemon Game onto your Pokemon Diamond Version.
The only other way is to cheat.
you cant sorry - Raymond laduke
Defeat all gym leaders in jounto and kanto then deafeat red and you can get another starter pokemon
Impossible. You'd have to trade to get all 3.