Updating the Nuclear Family as legit threats. Given how silly they appear as a concept, it's nice to see them treated as a serious threat, even to the likes of Firestorm. Dad and Sis get special mention since they are the ones that knock Firestorm around the most, and also how intelligent Dad is as the leader.
The whole episode Nuclear Family Values is a CMOA for the show and staff, forming a story of its own while still telling the origins of Firestorm and the Nuclear Family.
Superman gets trapped by Steppenwolf on a planet with a red sun and is slowly losing his powers. What does Supes do? Beat Steppenwolf, a general of Darkseid, with traps, quick thinking, and determination. He even manages to (once again) beat Batman and Barda's score.
Cyborg being able to outplay and outsmart Toyman with his own toy. Heck, the League vs. his killer toys is cool, and Toyman himself gets one for getting the drop on the DC Trinity and Cyborg.
How's this? Wonder Woman lassoing Superman AND Lex Luthor...OUT OF A BLACK HOLE!
Etrigan's Debut is rather awesome, especially given that he flips off a demonic Batmobile mid-fight.
Wonder Woman using the Lasso of Truth to reveal Lex is using Circe, and getting her to take back the magical talisman.
Zeus!Luthor vs. Superman is a pretty cool sight, especially with him throwing lightning around.
An all-out battle between Lobo and a teamed up Justice League and Red Lanterns.
How about we give a praise to the fact THE RED LANTERNS are MORE then just angsty and raging psychopaths for once!
While they are kids, the hexed versions of the Justice League mystics and Batman taking on Klarion with a mix of their usual skills and halloween treats is actually pretty cool to see.
To add to that? He saves ALL OF THE CITIES BRAINIAC HAS STOLEN! That's several million lives he saved!
Firestorm reverse-engineering the Kryptonite formula from a single piece and using it to bring down Zod and his cronies.
Professor Stein tricking Mr. Mxyzptlk into saying his name backwards and putting an end to his body-swappingmadness.
Constantine is awesome in "Supernatural Adventures in Babysitting".
Most of Zatannas scenes in "Hat Trick" certainly counts.
"Time Out" as a whole is one for Booster Gold, but especially the speech he gives Batman:
Booster: It's like...it's like when you have rats in your attic, and you call a guy to get rid of them. But, nobody ever sets out to be the rat guy. But somebody's gotta do it anyway. And that's me. I'm time's rat guy.
Mr. Miracle has one in Itll Take a Miracle!: When Darkseid asks for the last part of the Anti Equation, Mr. Miracle casually takes it out... and a Mother Box, which he then uses to transport Darkseid out.
It wasn't just any Mother Box either. It was Darkseid's! He took it right off his belt without being noticed!
"System Error" sees the robot League Darkseid built rebelling on Darkseid and thwart his plans to use the information gathered against the League.
In "The Goddess Must Be Crazy" short, Wonder Woman and a possessed Supergirl come to blows. The battle is as destructive and awesome as you'd expect from the world's mightiest female heroes.
Bizarro has "Boo-Ray for Bizarro": By allowing Amazo to copy his abilities, the robot also copied his backwards logic. This way of logic ends up being a huge Logic Bomb on Amazo's mind, short circuiting the android long enough to be detained. And this was after Amazo made short work of the Justice League members!
The writers get one for the fact that in some, if not most, of the episodes the day is saved not with punching but through the heroes intelligence and teamwork; a nice and subtle lesson for the viewers at home.
Though the occasional fight scene is not remiss.
And not to mention that the writers are able to make the stories cohesive and make sense, despite the fact of the shorter running time makes us go right in the middle of the occurrences, making it seamless in most situations.
The short "Missing the Mark", where Mark Hamill shows off his voice acting skills by playing 4 voices - Joker, Trickster, and Swamp Thing, and introducing Mark Hamill as Himself! I think the fourth wall collapsed under the strain!