"The Talkartoons series began to take a new direction with the arrival of Max and Dave's brother, Lou Fleischer, whose skills in music and mathematics made a great impact the studio. Fitz evolved into a character named Bimbo, named so for his foolishness. The first cartoon that featured Bimbo was Hot Dog (1930), the first entry in the series and the first Fleischer cartoon to use a full-range of greys. New animators such as Grim Natwick, Shamus Culhane, and Rudy Zamora began entering the Fleischer Studio, with new ideas that pushed the Talkartoons into a league of their own. Natwick especially had an off-beat style of animating that helped give the shorts more of a surreal quality.
Perhaps his greatest contribution to the Talkartoons series and the Fleischer Studio was the creation of Betty Boop with Dizzy Dishes in 1930.
By late-1931, Betty Boop dominated the series. Koko the Clown was brought out of retirement from the silent days as a third character to Betty and Bimbo. By 1932, the series was at an inevitable end and instead, Betty Boop would be given her own series, with Bimbo and Koko as secondary characters. " (Source: Wikipedia)