Super OVA 1: Based on a story from vol. 27 of the manga, Shampoo and Ukyo arrange to travel to a cave that is legendary for breaking up couples. They hope they will cause Ranma and Akane to break-up and Shampoo hopes to ditch Mousse the same way. 
Super OVA 2: "Jaaku no Oni" (lit. "The Wicked Demon") was released in 1995. Based on a story from vol. 29 of the manga, an Oni (that wears a tiger-striped diaper just like the Oni of Urusei Yatsura) escapes it`s sealed box and begins to possess people in the neighborhood. 
Super OVA 3: This is a story from vol. 31. Ranma disturbs a doll that takes revenge on anyone that shows it disrespect. In order to teach Ranma a lesson, the doll possesses Akane and tries on many occasions to attack him. 
(Source: AniDB)

Ranma 1/2 SUPER