Rufus Earning His Happy Ending in the feature length pilot, perhaps most notably risking the wrath of the Frazznats (one of few things established to kill an Urpney) to get back the Dreamstone.
In his faceoff with the Whirlyped he manages to fend off it's claw by biting it with his Cute Little Fangs. Rufus' teeth can penetrate metal.
While usually having a more cushy time stopping the villains afterwards, the Noops still perform occasionally impressive stunts to get the stone back in later episodes. "A Day Out" is a pretty noteworthy example, elaborately sneaking through Viltheed and snatching the stone from Zordrak via a split second opening.
Zordrak, usually an Orcus on His Throne, also has an Awesome Moment in his scene. While always menacing and sinister, his plans rarely expanded past giving the Noops bad dreams originally. Here he makes a full Badass Boast of his plans for his new treasure; to take it to the Nightmare Planet and corrupt it into evil, so he can use it to crush his enemies and become "LORD OF THE UNIVERSE!!!". The Noops creeped out expressions throughout sell that things are a lot more dire for them from this point on.
Let's be honest, while they were villains, it was impossible not to find any time the Urpneys did something competent somewhat gratifying:
In "The Spidermobile", the Urpneys spend the entire episode on top, using Urpgor's Spider Tank to curbstomp the entire Wut army and take the stone handily. Then when Pildit and the Noops come to take it back, they quickly neutralize them again, dragging them to their cell while they can only moan indignant. For extra points, they actually avoid their usual Humiliation Conga, Zordrak ends up taking the fall instead (quite literally).
In "Albert's Ailment" the Urpneys actually win hand to hand combat with the Noops and Wildit (one of the most formidable Wut soldiers) and tie them up. They were mere seconds from destroying the stone as well (and probably would have succeeded if not for a sword and speckled yellow mushroom all conveniently placed in the heroes' cell).
"The Dream Beam Invasion" was the nearest the Urpneys ever got to spoiling a victory for the heroes. After a night of successfully ruining the Noops' dreams, the heroes catch on and stop them the following night, however not before Frizz and Nug shrink into a dream and do their job. An angry Rufus, Amberley and Albert in turn shrink into the dream to start their usual Disproportionate Retribution, however just as the Urpneys are ready to surrender, their spell runs off, turning them giant in comparison. After one mean Death Glare, the heroes decide they Know When to Fold 'Em and make a dash (and pratfall) out the dream screaming in terror! To clarify, Frizz and Nug made the Noops and even Albert petrified of them.
Zordrak's face off in "Megattack", finally leaving his lair to unleash a full scale invasion on the Land Of Dreams. The heroes know they are outmatched so call upon the Planet Dreamstone, leading to an epic Beam-O-War. The Noops get a mini Awesome Moment by managing to deactivate Zordrak's hovering throne before he gains the upper hand.
After Urpgor is fired by Zordrak in "The Nightmare Stone" (the title trinket rendering his inventions redundant), he manages a secret coup that disposes of the stone and leaves the overlord having to beg him back (or more accurately, get Blob to beg him instead). Urpgor is a sniveling toady but he does not take rejection well.
He does it again in "Return of the Nightmare Stone", pulling an Enemy Mine with Rufus and Amberley by directing them to destroy the titular stone.
He and Blob's squad also neutralise and capture Zordrak's new minion, a solid Argorrible, to avoid redundancy in "Horrible Argorrible".