I hate ninja turtles (who came up with THAT idea!? even sillier than biker mice from Mars or whatever it was)
Teenage Mutant Ninja Turtles actually predated the Biker Mice by a decade. They were originally a black and white comic book, intended as an underground parody of Frank Miller's style, and were originally pretty gritty and violent. They were a big hit in the alternative comics world, and spawned dozens of imitators (Adolescent Radioactive Black-Belt Hamsters for example - I'll never forget that one).
A few years on the original creators (Eastman and Laird) sold the license. TMNT got modified (made lighter and sillier), and became a massive hit in the mainstream pop culture, spawning a second wave of imitations, which the Biker Mice were part of.
Licensing is a sword with at least two edges.