You don't not unless you trade or cheat
You go to professor britch and he gives the fire red starters
All Pokemon from Kanto, Johto, and Hoenn can be obtained in Emerald. Susrskit, Masquerain, Meditite, Medicham, Roselia, Zangoose, and Lunatone must be traded from Ruby or Sapphire. Other Pokemon like all of the starters must also be traded over.
Cyndaquil and all other pre-fourth generation starters are unavailable in Pokemon pearl and diamond. You must transfer it from Pokemon Emerald. If you do not have Emerald, sign up on a Pokemon trading forum and find someone who is willing to trade you one.
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.
cheats
you get them by catching all 200 Pokemon
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.
You don't not unless you trade or cheat
Yes you have to trade because you can't get all the Pokemon alone.
You can get it by transferring the Johoto starters via your Game Boy Advance to Pokemon Emerald
The only 2 ways to get johto starters is to see all Pokemon in emerald, and beat mt.battle in Pokemon XD and then send them to ur gameboy adv.
emerald isn't on there
Just migrate from the past games Pokemon leafgreen/firered or ruby/Sapphire/emerald. Then you will have them all.
You can never find the starters in the wild you can though find johto pokemon.
You go to professor britch and he gives the fire red starters