Darth Vader: To access Darth Vader you must beat the game on Jedi with Luke Skywalker. After you do this, a message appears on the screen that says, "Darth Vader Released".
Slave Leia: We all knew that Leia in that great gold bikini would have to be in this game! Yeah Baby! To access Slave Leia you must beat the game on Jedi with Princess Leia.
Stormtrooper: To fight with a stormtrooper, you must beat the game on Standard or Jedi with Han Solo.
Biker Scout: To Fight with a biker scout , you must beat the game on Standard or Jedi with Han Solo. You release a stormtrooper. Go to the stormtrooper and hold "L1" and then press X.
Jodo Kast: Win 7 matches in survival mode on Jedi and Jodo Kast is released. Earlier I had 10 matches down for this...Thanx to Triccie for clearing that up.
Mara Jade: On Jedi mode make sure the main screen highlight is on Team Mode, press and hold "L1, L2, and R1" then press X. The game will then select Luke, Leia, Han, and Chewie for you and the bad guys for the computer. Beat them all and Mara Jade is released.