Complex sentence: By the time of the 1932 cartoon Minnie the Moocher, Betty Boop could stand her own against the popularity of the Disney shorts; indeed, Fleischer would be considered Disney's primary rival in the 1930's.
Split into simpler sentences: By the time of the 1932 cartoon "Minnie the Moocher", Betty Boop could stand her own against the popularity of the Disney shorts. Indeed, thanks to Betty Boop, Fleischer would be considered Disney's primary rival in the 1930's.