Seeing as the Galaxy Rangers are a Badass Crew, it's hard to pick out some of the truly awesome. However, a few of the guest stars can really pull it.
The pilot episode, "Phoenix." Eliza does not get a lot of screentime before her Fate Worse than Death, but she really gets a good one. She puts her kids in an escape pod and goes back for more supplies. Waiting for her in the cargo hold is an alien pirate. He's armed, she isn't. She fights him off with a little distraction from the ship's AI and ends up blasting him with his own gun after making a Heroic Sacrifice in telling GV to launch the kids' escape craft without her.
Ariel: "Haven't you heard? War is deception - and illusion is a specialty of mine... now that you've used up so much power on the student, let's see how you do against her mentor!"
Zozo proves looks are deceiving as hell. He's a bit over a meter high, and a Badass Normal from a race of Hobbits. What he lack in size and superpowers, he makes up for in sheer balls. One instance has him jumping on Eldritch Abomination Scarecrow and hanging on for dear life as the creature fired blindly to try and shake Zozo off - this after Scarecrow had murdered the local sheriff, the deputy, and taken out the two Series 5s assigned to the mission. The Scarecrow's shooting triggers a fire and Zozo shoves it into the blaze.
Another good example was how he snapped his best friend out of insanity. The normally prim and rational Andorian Waldo had been reduced to a feral state, as captivity is so repulsive to his species that they go crazy from it. Zozo doesn't plead with the crazed Waldo - he just asks his friend to solve a simple mathematical equation, which gets Waldo to stop long enough to shake off the crazy.
"Heart of Tarkon:" an Evil Chancellor is trying to sell out Tarkon to the Queen of the Crown. Doc runs after him, but stops to pick up a sword. Turns out the hacker is a very impressive fencer on the side. Swords clash, insults get thrown, and Doc hands the traitor his ass, admitting that he picked up swordplay in "charm school."
In "Heartbeat," he uses the sword again - in mid-air, strapped to a kite. The Scarecrow (an Eldritch Abomination and one of the show's nastiest foes) is strapped to a second kite on another airship. The pair are fighting it out hundreds of feet above the ground in the middle of a thunderstorm. Doc manages to evade the Scarecrow's attacks and maneuver his kite to where he can whip out the sword and slash the Scarecrow's kite, sending the creature plummeting to the ground. No, it doesn't kill the thing - it's practically immortal. Still, the fact that Scarecrow managed to almost kill both Shane and Niko, but got solidly defeated by the team's Badass Normal is impressive.
Two Crowning Moments of bluff comes in "New Frontier." The first is when he stays outside to keep watch while the other three go into the Bad-Guy Bar to find an informant. The other three soon get ambushed, and when the cybersteeds and Doc come crashing in Doc buys them time by shouting that the bar's surrounded by "hundreds of Rangers," distracting the ambush long enough for the others to mount up and run. The second is when they're trying to break into an airlock in the Supervillain Lair. Doc jams the com signals of the Mooks guarding the door and feeds them a line of BS about their phone bill, leaving the others to blast them while they're distracted.
While her mentor was having her Crowning Moment, Niko manages to pull another. Her charge exhausted by the Megamind's earlier attack, and Ariel on the ropes, she pulls out a device Q-Ball was using earlier to test Zach's bionics from her belt pouch and uses it to remotely activate Zach's Arm Cannon to attack the thing from an angle it least suspected.
Recovering from being shot by the Scarecrow, Niko's still in bad shape when the thing comes in to try and finish her off. Goose busts in and fights it, only for it to get the upper hand. She shouts at Scarecrow to "Eat Light!" and gives him both barrels of her futuristic shotgun. We see a few seconds later she was only standing due to Heroic Resolve.
Zachary moving a massive ship cannon into position and then charging the damn thing with his bionic arm to deliver a crippling blast to the Crown flagship in "Armada." Let me say this again: The dude blew up a goddamn battleship with his arm.