U have to pick one starter for example piplup than u trade the other to
By trading the other starters with other players of Diamond or Pearl.
get one at the beginning and trade the others
It's impossible -- you must trade to get all three.
sorry but you have to get another diamond/pearl/platinum game and trade the other starters from there.
To obtain all three starters you need to trade with someone.
yes if you trade them in jubilife city
Trading.
You can first collect all of the Pokemon for the hoen dex in Pokemon emerald you will get 1 of the 3 Pokemon gold/silver/crystle series starters then use the get all of the starters trick to get them all then migrate them to Pokemon diamond or pearl.
Starters: Twirtwig,Chimchar And Piplup Starters(Evolve Forms:)Grotle,Monferno And Prinplup Starters(Final Evolve Forms)Tortera,Infernape And Empolion Still... I'm The Smart Kid.
U get all starters by getting another game or someone to trade u them
in my heart
It is not possible to get all three starters in Pokemon LeafGreen without trading. This was an intended mechanic to encourage interaction between players.