If you're looking for anime similar to Doraemon Movie 20: Nobita Gets Lost in Space, you might like these titles.
The film is set on the moon and centers on strong friendships bound together by the "ability to believe." Luna is a mysterious girl who lives on the far side of the moon. Diabolo and his subordinate Goddard stand in the way of Nobita and his friends on their moon exploration journey.
Doraemon and Director Burger try to set up a dramatic world where Nobita and his friends can truly become Space Heroes. However, the team soon finds out that Director Burger's scenario has come to life, and there is actual danger. Doraemon, Nobita and friends must work together to save Aaron and his home planet Pockle from space pirates.
Following an argument, Nobita follows Doraemon to the North Pole where he finds a strange ball that causes pieces of a giant robot to fall from the sky. After the pair builds the robot in the uninhabited Mirror World, Shizuka accidentally destroys a building with its weapons, and they decide it's best to abandon the robot and keep it a secret. The following day a mysterious red-haired girl named Lilulu begins to enquire about the robot, but after swearing Nobita to secrecy and borrowing the portal to the Mirror World she disappears. A few nights later Nobita follows a strange light and finds the portal to the Mirror World, though when he and Doraemon enter, they discover that Lilulu is building an entire army of robots! As the only ones to know of her plan, it is now up to Nobita, Doraemon and the gang to stop the Robot Empire's plan to invade Earth and enslave humanity.
After Suneo bragged about having a ranch, Nobita was asked whether or not he has one, pressuring him to say yes. Doraemon won a number of lotteries for useless planets in the belt between Mars and Jupiter. When Suneo and the rest came to see the ranch, Nobita happened to read the last of the lottery number to the go-anywhere-door, leading them to a huge dreamlike area. As Nobita's toy horse pranced around because of the wind-up life gadget, Suneo and the others became interested in doing the same to their toys and let them live in the area. So they decided to make their own clockwork city.
Nobita has been having a weird dream about a boy named Roppel and his strange companion Chami traveling in space. By a twist of fate, he met them in person where it turns out that they are real and that they were being pursued in space, causing their space vehicle to malfunction, connecting the space vehicle itself with Nobita's room. They journeyed to Roppel's planet and amidst their enjoyment, Nobita and Doraemon pledged to help Roppel's planet free from their oppressors.