In Episode IV: A New Hope "Death Star Escape", after you chase a Stormtrooper down the hallway, you will be bombarded with a large number of Stormtroopers. In Free Play mode, use a bounty hunter to throw a Thermal Detonator. When it hits the ground, set it off. It should wipe out a good majority of the Stormtroopers.

In the "Death Star Escape" level when you are in the room with the squad of Stormtroopers, use Boba Fett's rockets in the midst of them with the Invincibility Power Brick on. You will have a sure win in that room.