The ending of "Bellboy Donald" counts both for Donald Duck and for whoever was in charge of censoring cartoons in 1942.
For detail, Donald had been putting up with Pete's bratty son through the whole cartoon and wants to punish him, despite the manager telling him he'll be fired if he does. what does Donald do? He sacrifices his job to give the brat his just desserts!
Donald: Am I fired?
Manager: Yes, you're fired!
Donald: That's all I needed to know!
"Sea Scouts" has Donald defeating a shark with one punch.
With a boost of Mickey's potion, Pluto viciously mauls Pete the dogcatcher in "The Worm Turns".
The same honor goes to a fly who beat up a spider.
And to a mouse who beat up a cat.
And to that same cat who beat up Pluto.
Several instances where Mickey goes action hero, like "Shanghaied" and "Two-Gun Mickey".
Minnie in "Pioneer Days". When Mickey is about to be killed by the Indian chief, she escapes her ropes, picks up a piece of hot coal and stuffs it down the chief's pants.
The 36 second-long fight between Mickey and Julius during the climax of "Runaway Brain" . Say what you will about the Nightmare Fuel in that short, but those have got to be the most epic 36 seconds Mickey Mouse has ever had outside of video games and comics.
Get A Horse for seamlessly having the characters go from tradition black-and-white animation to color CGI and vice versa.
Mickey's method of dispatching Pete definitely counts.
Alpine Climbers had Donald successfully head-butting an adult goat.