Doraemon: Nobita and the Steel Troops (1986)

The story begins with Nobita and Shizuka sitting on the pipes in the yard they hang out at while Suneo showed off his robot. Nobita grew jealous and asked Doraemon to build him a giant robot. Coincidently, robot parts began to fall from the sky. Then Nobita and Doraemon began to assemble the robot.