If you are vastly outnumbered with Stormtroopers blasting left, right and center and you have R2-D2 in your party, use the following trick. First, make R2 your active character. Enemies will never shoot at a droid. Then, push the Stormtroopers closer to your friends then zap them with R2's electric prod type weapon. They will promptly stop shooting and rub their sore spot. Quickly switch to a member which has a piece that can do damage (for example, Han Solo or Luke Skywalker). Shoot the Stormtrooper while he is nursing his laser burn. After he is killed, make R2 your active character and repeat the process until you are victorious.