Yes, more starters. But this will only give you the starter you chose from Steven Stone, Professor Elm, and|or Professor Oak.
First, you need the starter you got from either of those people. (Blastoise, Typhlosion, Marshtomp, etc.)
Then you need a Ditto.
Ditto can get you eggs when you pair it up with most Pokemon.
Anyway, you can find it on Route 34, Ceruleun Cave, and maybe a few other areas in Kanto or Johto.
Put both the starter and Ditto into the care of the Daycare on Route 34. Run|Walk around until the Daycare Man says that your Pokemon had an egg. Retrieve the egg from him and run around with it until it hatches. The Pokemon that hatches should be the 1st Evolution form of the starter (Squirtle, Cyndaquil, Mudkip, etc.) you put in with the Ditto.
They are good Pokemon to offer on the GTS [Global Trade Station in Goldenrod] or for other people.