"Never Ape an Ape Man" has a MASSIVE one for Scooby: When the titular monster starts shaking a bridge - while an actress is still on it - Scoobyraces onto the bridge, barks and snarls at the Ape Man, and stabilizes the bridge while she gets off - by flattening his body against it to keep it from shaking. Then he proceeded to FIGHT the Ape Man using a branch as a trampoline and managed to land some good punches and kicks.
In a later encounter with the Ape Man, Scooby actually snarls like a wild animal and gets it to back off!
In "Jeepers, It's The Creeper," Velma is cornered by the Creeper and asks him "You wouldn't hit someone with glasses, would you?" The Creeper grabs Velma's glasses and rears back to sock her, but then she kicks the Creeper in the shin, reclaiming her glasses and running off.
In one of the old episodes, "A Gaggle of Galloping Ghosts", Scooby gets one by dropping the cowardly part of his Cowardly Lion persona, by tying up the villain around the legs with rope and dragging him to a trapdoor.
Before this, he proceeded to try scaring the villain by acting as a werewolf himself-growling the whole time and using piano keys as makeshift fangs!
In "Bedlam In The Big Top", Shaggy and Scooby defeat the Ghost Clown by using a mirror to make him hypnotize himself.
This is a Crowning Moment for Shaggy in particular since he was the one who came up with the mirror idea in the first place after Fred's plan had failed. And he volunteered to personally oversee the plan without demanding any Scooby Snacks!
"Decoy For a Dognapper" has a collective one for Shaggy and Fred. Scooby has been found out and sent on a ride down the train tracks, enclosed in a crate. Shaggy jumps out the window of the Mystery Machine onto the rail car, while both are moving. He then proceeds to outrace a train. Fred, observing the problem, races the Mystery Machine back and shifts the rails, rerouting Shaggy and Scooby to a safe position, moments before the train whooshes by.
"That's Snow Ghost" has Scooby rescuing Velma, who was chained to a log and headed for a circular saw. He then uses his tail as a motor to jettison them both away from a log with a cache of dynamite tied to it which the Snow Ghost sent behind them.
The trap scene of "Nowhere to Hyde". Fred, Daphne, and Velma dress up like the Monster of the Week and "scare the hide off of Hyde" so badly that he falls through his own Trap Door.
In "Scooby-Doo and a Mummy Too", Scooby and the mummy are both bouncing on a trampoline in the college gym, with the mummy trying to grab Scooby every time they reach the same height on the bounces. At the top of his bounce, Scooby grabs onto some gymnastics rings and kicks the mummy when he comes back up, so hard that he goes flying across the gym and gets caught in a basketball net.
In "Backstage Rage", Scooby spots a mysterious puppet master working the life-sized puppets on a catwalk in an old stage theater. He proceeds to get up there himself and CHASE the puppet master down the catwalk before cornering him onto a rope. Fred then brings the figure down by cutting the rope. Not bad for a cowardly dog!
"Hassle in the Castle"
In order to get Scooby to be brave enough to distract the Phantom so they can catch it, Fred tells Scooby to think of dog actors like Lassie. The one that gets Scooby motivated? John Wayne.
The gang set up an elaborate trap to catch the Phantom...and wind up catching Scooby instead. The Phantom then taunts the gang, saying they can't escape him now, only for Scooby to fall out of them trap and right onto the Phantom himself.
Heck, even the theme song includes an awesome moment. Upon finding Scooby, the singer says that Scooby is ready and willing, despite his cowardice. And knows that if they can count on him, they can catch the villain.