Sonic the Hedgehog (OVA)

Sonic the Hedgehog: The Movie
Sonic the Hedgehog: The Movie, which is also called Sonic the Movie, is a movie about the Sonic series released in 1996. It was later dubbed into English by ADV Films and released in the U.S.A. on September 9, 1999.

Plot
Sonic and Tails are enjoying a day at the beach when they find out that Doctor Robotnik (who is called Dr. Eggman in the Japanese version) kidnapped the President and his daughter Sara. Robotnik tells them that his city, Robotropolis (Eggmanland in the Japanese version) has been taken over by a giant mechanical version of himself called Metal Robotnik (Black Eggman in the Japanese version). The Robot Generator was sabotaged because it was overloaded with energy, and Robotnik says it will malfunction, destroying the whole planet by tomorrow. Sonic goes to Robotropolis and defeats Metal Robotnik, not aware that it was a trap devised by Robotnik to copy Sonic's DNA to make a new robot, Metal Sonic. When Metal Robotnik is defeated, the cockpit breaks open revealing Robotnik and Sara. Robotnik then reveals Metal Sonic, who fights the real Sonic and wins.

Back in the Land of the Sky, Tails learns Metal Sonic is trying to destroy the world by digging into the ice caps that holds the Land of the Sky together, allowing lava to flow in and melt the ice. Sonic hears about this from the President and Knuckles. Tails, Sonic and Knuckles all go to the ice caps, where Robotnik, whose goal is to destroy the world so he can rule the planet with Sara. Sonic and Metal Sonic have a long fight, and Metal Sonic falls into the lava. Sonic tries to pull him out, but Metal Sonic pushes Sonic's hand away and says "There is only one Sonic."