Scooby and Scrappy-Doo premiered on September 22, 1979. This cartoon
introduced another character to the cast: Scooby's nephew Scrappy-Doo, whose main
purpose was to splat ghosts while the gang tries to run away from them.
In November 1980, this show was known as The Richie Rich/Scooby Doo Hour,
which only featured Shaggy, Scooby, and Scrappy in three 7-minute short
segments, and was shared with Richie Rich, the adventures of Richie Rich and his dog Dollar and his robotic maid. These shows shared an hour for two seasons.
In 1982, Scooby and Scrappy Doo shared an hour with a cartoon about Pete the Puppy and his friends and also had three short segments, the third being a Yabba-Doo cartoon,
one of Scooby-Doo's cousins who lived in the Wild West. This show was known as The Scooby-Doo/Puppy Hour.
The show was revamped as The New Scooby-Doo and Scrappy Doo Show in September 1983, and brought Daphne back to join Shaggy and the dogs in solving mysteries. This cartoon consisted
of two segments, and was often combined with repeats from previous seasons.
In 1984, the show underwent another name change and was called The New Scooby-Doo Mysteries, which brought back the original gang.
Oh and in 1990 new episodes were aired!