You'll need a spare game cartridge, either Ruby, Emerald or another Sapphire. You set up a new game on your Sapphire game cartridge and choose any starter. Then go out and catch any 2 other Pokemon. Now that you have three Pokemon (one of which is a starter), start a new game on the spare cartridge and choose one of the starters you don't have. Go to the Pokemon Centre on both games and trade the starter on the spare game for one of the Pokemon you caught on your Sapphire game. Save and turn off. Then start a new game on the spare cartridge and do the same for the remaining starter Pokemon you don't have.
You need a game sharkYou need a game shark you can also get them from emerald but you have to complete the pokedex in emerald to get oe of the three starters from pro. berch
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 don't not unless you trade or cheat
get one at the beginning and trade the others
By trading the other starters with other players of Diamond or Pearl.
3314775
either you hack them or you don't get the others at all. simple as that
you just pay 300 eCoins
Torchic, Mudkip, and Treecko
The three starters: Mudkip, Torchic, and Treecko.
To obtain all three starters you need to trade with someone.
the starters in sapphire are treecko, torchic and mudkip
You need a game sharkYou need a game shark you can also get them from emerald but you have to complete the pokedex in emerald to get oe of the three starters from pro. berch
Trading.
In Pokémon Ruby (and Sapphire/Emerald) the three starters are Treeko (Grass type), Torchic (Fire type) and Mudkip (Water type).
you can not! if you trade with ozers only!
in my heart