Mrs. Jumbo locking the mean elephants in their stall.
She also smacks a boy for teasing her son.
The ringmaster locking her up was his Moment of Awesome in the same scene. You wouldn't think a human, much less an unthreatening-looking guy like him, would be able to subdue a rampaging elephant, and yet he does.
Timothy Mouse gets his good moment by scaring the other elephants for picking on Dumbo.
The crows teaching Dumbo to fly.
Before that, Timothy's speech calling out the crows and the world at large for mocking Dumbo's ears.
Dumbo shooting peanuts at the mean elephants like bullets from a gun is his way of saying "Take That!"
As mean as she may be, the Matriarch gets one for showing her Badass credentials as a circus elephants. She stood on one ball and being ridden upon 6 more elephants and despite sweating all over, manages to keep her balance (until of course, Dumbo ruins everything, but even then she keeps herself above the ball for a long time). By the show's standard, she's a meanie for bullying Dumbo, but if you're looking for a circus elephant for high-level stunts, she's the elephant you're looking for.