Kreia
She gives everyone an earned experience bonus. Even better, the unique bond she shares with the player allows him to Force Chain attacks and defense. Any Force Power cast on Kreia or the player will be automatically applied to the other party members as well. The exp bonus works like this: It's a percentage. The amount of the percentage goes up as Kreia goes up in level. The stages are 3%, 5%, 7%, the levels are at 1, 7, 13.
Atton Rand
Cannot be knocked unconscious while other party members are still standing,
Says "I've got a bad feeling about this" at certain points before dangerous situations, as a prompt to save.
Resistance to paralysis, poison and stunning
Mira
Mira fire can rockets at opponents, but her launcher can also do the same things with grenades. There's also single-shot darts that can target single opponents as well.
Another ability Mira has is called 'Point Guard'. Whenever she's leading the party (I.e., you are actively controlling her), the party will not set off mines. Also, she will never set off mines herself, even when she isn't the leader.
Bao-Dur
His arm allows him to 'bash' down certain force field doors quickly. His robot will help you in combat by shooting enemies or repairing friendly droids. He upgrades it over the course of the game.
Visas Marr
Permanent Miraluka Force Sight (You access it by pressing the right thumb stick)
Wookiee
He has the ability to enter a "Wookiee Rage," Chewbacca style, make the screen flush blood-red and then proceed to rend through any opponents they encounter. Don't forget to use it if your wookiee friend is in a tight spot.