Okay I have finished the emerald need to know how to get the three starters or just the one from my game any help greatly appreciate it. Thanks

Complete Mt.Battle 3 times in pokemon XD.

If you complete the Hoenn PokéDex (Excluding Jirachi and Deoxys), and talk to the Professor, he will give you one of the starters. (You get to choose)

I appreciate you guys trying to help but I really don't understand none of this. I have already caught 201 on my national pokedex and have talked to professor birch and he hasn't given me anything. Is there something else I need to do?

The key here is to catch ALL the pokemon in the Hoenne(spelling?) dex.That means all from Treeko to Rayquaza.(you don't need Deoxy or Jirachi as someone already said). When you have all the pokemon in the Hoenne dex talk to Birtch at his lab and he will offer you a choice between the Johto starters.You can only have one (unless you gameshark or trade over from other games)so choose cearfully.

Get a tododile. Awesome at alllll stats!!!!!

How do you know when it's from the Hoenn dex?

I'm pretty sure you can switch between Hoenn and Nat. once you get Nat.

Pick Cyndaquil(Spelling?)he is a very good fire pokemon and he can do moves like Rock slide,Thunder punch,and more.

get tododile.when he evolves all the way 2 feraligator its so worth it!(cant spell worth the crap)

I found the hoenn index. I forgot that is was there, I'll be able to get all the hoenn pokemon but may have trouble with feebas to milotic.

Not the national dex, but Hoenn dex.
People are going off-topic here. Snowball has already given us a link to CHickorita's locations, which includes how to get it on Emerald. People don't need to give opinions about wich starter should be chosen, each one has their own preferences, and that's fine; this is not the subject of this thread. I'm pretty convinced that the question has already been answered.

Mod Edit: Indeed. *Locked* (7/1)