Cloud City 4-20 is the twentieth level of Cloud City. To pass this level with three stars, you should pop all pigs and score at least 93,000 points.
Send Han straight ahead, blasting the first switch to open the first gate. Unfortunately, the second barrier is closed by the same switch, so try to get through before it closes. Use Leia to grab the chain boulders, then Obi-Wan to push blocks into Vader, then send Luke to clear the remaining pigs. Han Solo can pass the second gate if lucky and deactivate the 3rd gate.