When you collect the indicated number of points in battle the corresponding Special character will become unlocked. These characters are worth using as they have abilities and skills that will help you in certain situations.

Unlock Bothan Spy:
Collect 8 points.

Unlock Clone Commander:
Collect 8 points.

Unlock Imperial Officer:
Collect 8 points.

Unlock Jet Trooper: 12 points

Unlock Magnagaurd:
Collect 8 points.

Unlock Wookie Warrior:
Collect 12 points.

Unlock Dark Trooper:
Collect 12 points.

Unlock Droidika:
Collect 12 points.

At the 'Main' menu select 'Instant Action' mode followed by 'Mos Eisley' as your level and 'Assault' as the game type. When you now begin a game you can choose to be either the heroes or villains and be able to fight any of the 'Hero' type character classes with no time limit.

In Single player mode, Pause the game and enter the corresponding codes for the following

Infinite Ammo:
U, D, L, D, D, L, D, D, L, D, D, D L, R

Invincibility:
U, U, U, L, D, D, D, L, U, U, U, L, R

Low-Resolution Soldiers (Single Player Only):
D, D, D, U, U, L, D, D, D, D, D, L, U, U, U, L

Party-Time Jedi/Wampa Hit Effects (Single Player Only):
U, D, L, D, L, R

Slow-Motion Sounds (single player only):
U, U, U, L, U, D, U, U, L, D, D, D, L, U, D, D, L, R

No HUD (Single or Multi-Player):
U, U, U, U, L, U, U, D, L, D, U, U, L, R