its simply not possible
Six without trading.
you can migrate him from emerald or sapphire.
You cannot get all 3 Starter Pokemon in Pokemon Emerald without trading for the other 2.
You cant without action replay
In sapphire you cannot get Groundon and Latios without trading or cheating.
You can't unless you picked it as starter pokemon.
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 don't.
unless you use a gameshark/codebreaker, you cant, sorry.
The only other way is to cheat.