All Recruitable Characters:

To get all recruitable characters, start a New Game. Beat it, and start a New Game+. Make sure you go in different paths such as this:

Game 1: Save Kid
Game +: Recruit Leena & don't save Kid.

If you do that, then on New Game++, this is what you do. Go to Sprigg's house in 2-D world with the Chrono Cross. Right when you get there, it will say that the world is reacting to the Chrono Cross. Go into Sprigg's house. Right smack-dab in
the middle of his house use the Chrono Cross as a key item. It will say that all your friends are re-recruited! Now there you have it!

*NOTE* Since you are Serge, Lynx will not be in your party. Remember a long time ago, when Lynx was the main character? That's why!