It was a cartoon movie in the 80's. It had a few mice and I believe the bad guy was a rat. It also had a real fat female mouse with blonde pigtails and wore rollerskates.

Fat,roller skating"mouse"
With pigtails

Did she go to a nightclub?

Sounds like the ditzy little sister
Of Mok's thuggish henchmen

Maybe,.
Rock and Rule (http://www3.bc.sympatico.ca/jcannon/rocknrule/)(83)
(a.k.a.Ring of Power)


In the distant future long after man is extinct due to a nuclear war, the stray dogs, cats and rats evolve into an intelligent humanoid species. The new inheritors of the earth rebuild civilization out of the burned out ruins.
An evil deranged music mogul named Mok, and his lackeys search the world for a voice with a special quality. The voice is the final element that Mok needs for an evil spell that will summon an all-powerful demon

They find the special voice in the form of a young female named Angel who sings in a small rock band with her friends and Omar, her boyfriend. Mok preys on her dreams of stardom and offers her a chance at the big time if she sings for him, but of course he has evil unspoken motives of his own.