Get Bulbasaur
After you get Squirtle, go to Cerulean city, and in one of the houses there is a lady, who has Pokemon next to her. Talk to her and she will ask you a question. Choose the top answer and she will ask you another question. Choose the top answer again and you get Bulbasaur!


Get Charmander
There are several ways to snag Charmander. On way is to travel to Ceruleon City, and talk with the man on the other side of Nugget Bridge. The other way is to beat SS. St. Anne to port and speak to Officer Jenny.

Get Squirtle
After getting off the S.S. Anne, and getting the Thunderbadge from the gymleader, Lt. Surge, then you can get Squirtle from Officer Jenny in the middle of town.