As soon as you complete your Hoenn Pokédex, talk to Professor Birch. He then will give you ONE of the three Johto starters: Chikorita, Cyndaquil, or Totodile.
Sadly, you cannot get all three unless you do one of the following:
Trade from another trainer
OR
Use Action Replay, GameShark, Or another game cheating device.
Trading.
You don't not unless you trade or cheat
two words: YOU HACK
T-R-A-D-E that spells trade (with someone) You need emerald , ruby/sapphire and a link cable. pick one of the three starters in emerald. then pick a starter that you didn't pick in emerald. then trade the starter over to emerald. then pick the starter that you didn't pick at all and trade it over to emerald. now you have all three starters in emerald! hope i helped!
cheats
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
Sorry, but the only way to get all the starters from Pokemon Crystal to Fire Red or to Pokemon Emerald is to get a gameshark and do it from there.
you get them by catching all 200 Pokemon
To obtain all three starters you need to trade with someone.
To get Johto starters, you have to use Emerald Version. You have to complete your Hoenn Dex (get all 200 pokemon) and you have to choose one of the three. Then (if you want them all) you restart the game and get them all again and choose a different one. sorry it's so hard!
You can only get one of the three Starters in Pokémon Emerald without use of cheating or trading. You can trade or use an action replay code to get all three (I don't know the code, so I can't help you there). Hope this helped.
beat the elite four get a gameshark and the code is:qw7av78cvbfhg4.=5544577 788955258858 4785dfvhrbdnqaz7 47852145ssdczskl;