After a tremendous loss of the Thunderzords to the hands of Rito Revolto, the Rangers get new Powers and new Zords, thus a brand new Megazord. What did the Rangers do with this new Megazord? They defeated Rito by PUNCHING HIM (which, to be fair is the Ninja Megazord finisher, so it wasn't just a regular punch).
To elaborate, Rito destroyed both the Thunder Megazord & White Tiger Zord in a Curb-Stomp Battle (in his debut, no less), which also caused an overload in the Morphing Grid & stripped the Rangers of their original powers. The rest of this opening story arc was about the Rangers gaining new powers & zords, and when they finally fight Rito in the Ninja Megafalconzord, they got to do the Curb Stomping.
Though he had 4 other monsters with him in the first battle (The Rangers never fought more than 2 at a time)
Actually, they fought 6 monsters at once with the Thunder Megazord and the White Tiger Zord during The Wedding and still came out on top. So it looks more like Rito was the deciding factor.
Also, until that time, the full version of the song "Go Go Power Rangers" NEVER went into its second stanza (Starts with: "They know the fate of the world is lying in their hands"). The fact that it does that to continue the fight? Made this fight (and the Megazord) more memorable. It showed that the team was back and ready for more!
One of the most memorable moments in the entire franchise was Jason finally defeating Tommy in a climactic battle at the end of the "Green With Evil" story arc.
The glorious moment when Tommy finally completes his Heel-Face Turn and joins the team as the Sixth Ranger. For added awesome, the Rangers combine the Dinozords and the Dragonzord for a new configuration.
Alpha 5 re-establishing contact with Zordon. The Big Good can then tell them how to break Rita's spell and also brings the zords back. In other words, the battle shifted in the Power Rangers' favor the instant Zordon returned. No wonder Evil!Tommy's first action was to trash the Command Center.
The Dinozords triumphantly returning in the last part of "Green With Evil", roaring (or in the Mastodon's case, trumpeting) as they rise out of the lava pocket Rita had trapped them in.
Given the White Ranger powers in the middle of season two, Tommy spent the second half of season two and the first half of season three beating monsters by himself (while both morphed and unmorphed), thrashing armies, and constantly saving the day single-handedly (almost to distraction. It got to the point where the show was basically Tommy And His Five Incompetent Friends). Then, in "Changing of the Zords part 3", Tommy charges into another dimension to rescue a kidnapped Kimberly (who, until Lost Galaxy, was as close to dying as any Ranger had ever been), finds Lord Zedd standing there, and confronts him - and Lord Zedd kicks Tommy's ass into next week in an epic one-sided curb-stomp (There wasn't another example of a villain so thoroughly pwning his Ranger counterpart for years afterwards, when Astronema nearly destroyed Red Space Ranger Andros). Zedd only loses through the fight through plot-mandated technicality but there's a very good reason that, even after 20 years, Zedd is still the reigning king of bad-ass Power Ranger villains.
In the same battle, Zedd comments on Tommy's kiai and then proceeds to do some of his own just to taunt him. It takes this CMoA to a whole new level. This was after Rita gave Zedd the love potion and put him through executive meddling inducedVillain Decay. Basically, Tommy, the in-universe "greatest ranger of all time," in his prime, had his ass handed to him by the watered-down, goofier, and quite possibly NERFED Zedd.
The "Changing of the Zords" saga was the best thing that ever happened to Zedd. He had those kids screwed. The only reason he lost was because he didn't expect the Rangers to cheat but that three-parter restored so much badassedness to Zedd. It was a long time coming.
The climax of "The Wedding"; the Thunder Megazord and Mega Tigerzord defeated an army of giant monsters and barely got a dent. (When you stop and remember how much trouble they all gave them the first time in individual battles, it truly becomes awesome.)
Continuing his bad-assedness in the multi-part story mentioned above, Zedd also visited the Power Rangers' secret HQ and then mocked everything, from Alpha's woobieness to saying that Rita could make a better interior decorator. A Big Bad would never enter a Ranger base again until Astronema briefly conquered the Megaship with brainwashed Teenage Mutant Ninja Turtles in the fourth episode. Divatox actually conquered the original Power Chamber but never went inside (also, given that Divatox is from Turbo, many people don't like to acknowledge her existence).
To elaborate, Zedd didn't break in or anything like that. He had those kids so screwed that they had NO CHOICE but to let him in. What made it even better was that he didn't have to go in. That moment was basically Zedd rubbing in his superiority.
"Save your breath, Zordon! I'm giving the commands around here!"
Adding to Lord Zedd's general awesomeness was that he got some of the best bad guy one-liners ever. When he was telling Goldar about his plan to send the Rangers on a never-ending scavenger hunt throughout the Universe, Goldar interrupted Zedd to praise the plan. Zedd replies, "Silence, fool! I wasn't done talking about me yet!" Some days, it was really hard to not cheer for Zedd, because he just did it with such style.
Let's just throw one more Zedd crowner in here: Serpentera. Zedd's own zord was the biggest and flashiest Wave Motion Gun in the series for many years, and still probably wins the Rule of Cool award. Of course, every time it appeared a Phlebotinum Breakdown was imminent due to a lack of Stock Footage to pull from, but most fans didn't care. Serpentera so outclassed any other weaponry in Power Rangers that fans wondered why Zedd abandoned it for a family RV in Zeo, and questions persisted for so long that it eventually would return in a special episode more than five seasons after it was quietly Put on a Bus.
Not to mention that the only reason that last appearance wasn't the most awesome thing ever, requiring more firepower than any other fight in ranger history, was Executive Meddling and budget.
Jason going one-on-one with Goldar led to a few of these:
During the "Green With Evil" arc, Jason fights Goldar and then evil Tommy... unmorphed! Sure, he doesn't win, but facing those two when they were at their Badass peak and surviving? Awesome.
During "The Green Candle", Jason charges into the Dark Dimension to get to the candle which is draining Tommy's powers, and finds that Goldar is there guarding it. Without morphing, Jason takes on Goldar in a one-on-one unmorphed fight — and this time he wins. Unfortunately Rita sends down a monster at that point and Jason has to leave without the candle (so as to save the lives of millions of people), but as a Crowning Moment Of Awesome, there's no way around the fact that it set the bar pretty damn high. Austin St. John called this particular fight his favorite from the show at Power Morphicon 2007.
Another entry for Jason is the entirety of "Crystal of Nightmares". Goldar activates the crystal, which leaves the five Rangers fearful and panic-stricken. When their communicators beep, it's Jason who takes charge, telling The Team, "I know we're scared, but we have to answer this." The world needs saving, and it's Jason who steps up, completely irrespective of his palpable terror. A few minutes later, the Rangers teleport to the cave housing the crystal. The Rangers are surrounded by putties and losing (thanks to their crystal-induced fear), but Jason sees a break and races into the cave. He then confronts Goldar (by this point, they'd established pretty strongly that there was one person who was a match for Goldar even without powers, and that's the guy wearing the red suit) and destroys the crystal with a well-placed kick.
Even in "Doomsday", when Goldar leads a troop of putties to Billy's house (to stop Billy from repairing the team's communicators), there's a point where the four Rangers back off as Goldar approaches, but Jason raises his arms and steps forward to meet the alien warrior. Even without powers, Jason was strong enough, brave enough, and confident enough, to throw down with the guy who's capable of thrashing the entire team. Even after 20 years, Jason is still my favorite Ranger, and that right there is the reason why.
Bulk and Skull in "When Is a Ranger Not a Ranger?" They risk it all to save the amnesic Rangers.
The comic relief duo getting their own Big Damn Heroes moment to save the Power Rangers, and succeeding? (Granted, they lose their memories of knowing who the Rangers are under their helmets, but still...) Awesome.
It's more than that. They first find out the Rangers' identities through genuine competence, they then work hard to help the Rangers recover their identities, using their hero-worshipping thing to great effect, THEN nobly and bravely they hold off the monster until the Rangers are actually able to fight it again. Easily their best moment until the "I Am Spartacus" bit.
Also a Crowning Moment of Funny, Kimberly is kidnapped by Goldar in an attempt to turn her evil so she can marry Zedd. When the spell doesn't work, Kimberly decides to have some fun with the situation and instantly turns herself into a Rita-esque Large Ham, loudly berating all the minions and even whacking Goldar a few times with her staff, making him deeply regret the whole thing. Double points for a near-spot on mimic of Barbara Goodson's voice.
Terror Toad, a monster in season one, counted as nightmare fuel for a lot of young fans at the time, but people tended to forget how the monster was destroyed. Kimberly arrives on the scene and rescues the other Rangers. The Terror Toad flees through the forest. With no time to give chase, Kim summons her Power Bow, fires... and we see the arrow flying around the forest like a guided missile after the escaping Terror Toad, dodging around trees before destroying the monster. So what did we learn? That the Pink Ranger carries around, as her standard weapon, a lightweight easy-to-use rocket-powered grenade launcher with unlimited ammunition.
Another moment for Kim comes in the Season Two episode The Song of Guitardo. First of all, she blasts the monster away using her Power Bow as a Harp, meaning she overcame the Power of Rock with a HARP of all things, then uses it to launch the Dragon Dagger at the monster, resulting in a most satisfying explosion.
When Tommy was on the verge of losing his Green Ranger powers (and to make matters worse, they'd go back to Lord Zedd if he used them again), Goldar taunts Tommy and tries to make Tommy say that Goldar is superior. Tommy's response?
The original Ultrazord sequences. When Titanus is called in, the Monster of the Week is screwed. Perhaps one of the best examples is "Doomsday, Part 1". The Tyrannosaurus Dinozord and the Dragonzord in Fighting Mode are on the ropes, at the mercy of Rita's War Zord Cyclopsis after having been nailed by its shock cables. Then Titanus charges in in attack mode, blasting them free. They form the Ultrazord and blast Cyclopsis to smithereens.
Most monsters knew this and would give up once they saw the Ultrazord. One exception was Samurai Fan Man who had beaten the individual zords, the Megazord, Dragonzord, and Dragonzord Battle Mode in an ugly Curb-Stomp Battle, so naturally he's overconfident as he charges the Ultrazord. We know what happens next.
Speaking of Cyclopsis: "Doomsday, Part 2". After the Megazord and Dragonzord were curbstomped twice by Cyclopsis (In the second battle, Megazord lost an arm and Dragonzord its tail), Zordon and Alpha find Cyclopsis weakness, which is that it adjusts to what it fights and can't adapt to quickly changing forms, and...let's just say that it's payback time for the rangers and the zords (this time, is Dragonzord who destroys Cyclopsis' arm blades with its tail), but still, he's like pre-power boost Cyclopsis which pwned them anyway until they do their last few transformations which locks the system.
Also, we can't forget the Thunder Ultrazord. Sure, it was just a big brutish contraption that flew up and landed on a monster but it bailed them out on numerous occasions. First after the Four Headed Monster bats back the Mega Tigerzord finisher the Thunder Ultrazord squashes it (after Tor gives the monster a taste of its own medicine) and even takes out Silverhorns who had such an easy fight with the Red Dragon Thunderzord that he seemed to be comfortable and enjoying himself (even unharmed by its finisher which had killed two monsters to that point). He also torments Tigerzord the same way. But then the Thunder Ultrazord comes in and saves the day. A modified version later on takes out Goldar and Scorpina (who seemingly were fed energy from Lord Zedd's staff as they were more powerful than before).
The final battle of the "White Light" saga (White Ranger's introduction) was full of Crowning moments. One saw the Red Dragonzord jousting the enemy... WHILE RIDING THE TIGERZORD. Then, a crowning moment of Badass, the monster blasted the Mega Tigerzord, but did nothing to it. In knowledge of this futility, the Megazord continued SLOWLY WALKING TOWARDS THEM, to let them stew in the knowledge that they were about to get obliterated.
That fight scene had a ton of crowning moments. Such as the first appearance of the Phoenix Grid, the Mega Tigerzord's finishing move that destroyed Nimrod. It was such an epic, awesome thing to watch. I still remember the first time I saw it, and my jaw dropped, it was so awesome. I would watch zord battles and just hope they'd summon the Mega Tigerzord, just so we'd get to see the Grid Finishing move again.
In fact, this was one of the few times the Monster of the Week came close to panic. (Her two assistants clearly did, trying to hide behind her, causing her to yell at them and shout, "Can't you do anything right?")
"Return of An Old Friend, Part 2": The Dragonzord had to fight alone against Goldar and Scorpina. It won.
"A Friend in Need, Part 2," before the throw-down, where Dex stands up to the Plague Patrol while backed up by five Power Rangers.
And for a meta Moment of Awesome, this was over a decade before Kamen Rider Decade. Yep, Power Rangers crossed over the two properties first. Say what you will about the eventual Masked Rider series, but the above is nothing short of badass.
In "Missing Green," Jason runs the gauntlet to save the other Rangers - fighting the Z-Putties, taking on the Pipe-Drain monster in his Zord and finally battling Goldar in the another dimension. He save sthe others' powers in the nick of time and even kicks Goldar in the face before escaping back to the Command Center.
The Pipe Drain battle deserves special mention because the Red Dragon zord is fighting without the benefit of the 'zord armor' it usually has. Not only does it win but this is the most one-sided zord battle in the series thus far. Jason uses the mecha mode as an extension of himself and floors the creature with his martial arts. When it briefly turns the tide with Tentacle Rope, Jason brings out the Red Dragon's staff and floors it a second time before killing it with the Finishing Move.
Tor the Shuttle Zord is able to withstand Serpentera's massive foot and prevents Zedd from crushing the Rangers. It also drains it of half its energy and thus forcing Zedd to retreat.
The entire zord battle in "Stop the Hate Master Part II". After the Monster of the Week was enlarged to city-smashing size, the Rangers didn't bother assembling the Megazord, instead fighting - and defeating - him with the individual zords. Indeed this was a Crowning Moment Of Awesome for the Megazord that didn't even require the Megazord.
Billy defeating The Brick Bully all by himself in a Zord Battle.