Source taken from Wikipedia.org
Dragon Ball Z: Return of Cooler, known in Japan as Dragon Ball Z: Clash!! 10,000,000,000 Powerful Warriors (Doragon Bōru Zetto Gekitotsu!! Hyaku-Oku Pawā no Senshi-tachi?), is the sixth Dragon Ball Z movie, originally released in Japan on March 7, 1992 between episodes 130 and 131. It was released on DVD in the United States on August 13, 2002. It also had a special theater presentation (as part of a double-feature with the U.S. premiere Fusion Reborn) on March 17, 2006. These movies are the first Dragon Ball-related movies to receive a theatrical release in the United States. This film, alongside Cooler's Revenge, was re-released in November 2008 alongside the remastered season 7 of the TV series.
A few years prior, the tyrant Frieza destroyed the Planet Namek during his battle with the newly transformed Super Saiyan Goku. The peaceful Namekians found themselves without a home for months. Eventually they had a new planet created for them with the help of the Dragon Balls. For three years or so they lived in peace on their new planet. One day however, a strange metal planet began to absorb New Namek within itself. The star buried its way and wrapped around the planet, absorbing its energy. Dende, who is now the Earth's guardian, senses the plight of his people and calls Goku to ask for help.