"Return to New York, pt. 3". The "final" showdown with the Shredder. Shred-head and Leonardo both leap, swords drawn. Two seconds after they land, Shredder's head falls off. Mind: blown—that sort of thing just doesn't happen in Saturday morning cartoons! Minutes later, after the end of the episode, Shredder's body stirs, gets up, searches blindly for its head, and picks it up. End episode.
Granted The Reveal takes away the sense of awe and fear factor, but back then we could only assume he was undead or worse. This kind of thing on a freaking 4Kids show was to many of us something we'd never see.
In the same episode, Stockman vs. everyone.
"Same as it Never Was." The whole thing. The fact that they were able to produce and show such a dark and bleak episode packed with character deaths on a saturday morning timeslot hosted by 4Kids is means for a pat on the back. Not to mention Donatello's method of defeating the Shredder counts as his personal Crowning Moment of Awesome as it's arguably the most badass thing he has done or ever will do.
AU/Future April taking out AU/Future Karai... with a rocket launcher!
And if it's not SAiNW, Back to the Sewers seems to be one giant love note to Don's fanbase— particularly "Hacking Stockman" and the finale, "Wedding Bells and Bytes". In the first he got the drop on the Cyber Shredder, fought him one-on-one, and, if memory serves, didn't even get hit once— it's an awesome mix of Beware the Quiet Ones and Papa Wolf tendencies, since Don was fighting to keep his brothers safe. The second seems a bit anticlimactic after that, but it was pretty awesome that he took out the Cyber Shredderwith the sameApplied Phlebotinumthat kicked the arc off. All this from the guy who is, arguably, the Squishy Wizard of the main team.
Savanti Romero, one of the Turtles' more obscure enemies, gets one when he fights the Turtles for the second time, but it's not during or after the battle though, it's before the battle even starts, he basically makes these dinosaur bones into Shredder-esque armor for himself, that's actually pretty awesome.
When Michaelangelo fought Kluh in "Grudge Match", he beat Kluh, which was a good fight to watch, to see the quirkiest character in the group put a beatdown on Kluh, right after Kluh put a beatdown on him, and does Michaelangelo finish Kluh off? No. He pushes Kluh down with a finger, and rightfully claims the title of Battle Nexus champion.
In that same episodes, there are more fighters of the same species almost equally powerful to Kluh who are holding the Dameo's son hostage. Leonardo defeats four of them by himself without trouble. According to Kluh's shocked father, this simply doesn't happen. Yeah, Leo's just like that.
In keeping with the Michelangelo theme here, the fact that he was able to fend off the Turtlebot in What a Croc a good ten seconds longer than the rest of them is definitely impressive, considering even Leo and Raph lost their bouts in five seconds or less. He's the one to finish it off, too.
The Shredder Strikes Back parts 1 and 2 was a Homage to an original issue of the Mirage Comic series, where Leonardo takes on what amounts to the ENTIRE FOOT CLAN by himself. He spends virtually the entire episode in one long running battle where he faces foe after foe and is never given the chance to recover, culminating in a battle with the Shredder's four elite warriors. That he loses does not actually detract from how awesome it is, especially when in Part 2 we see the same Foot Clan attack the three remaining Turtles and Splinter, and we see that Leo basically did as well against the Foot by himself as his family did working as a team.
And then there's that moment in Part 2. All four turtles are down and the Foot is advancing on them when Casey Goddamn Jones crashes through the window on a motorcycle, promptly disposes of half-a-dozen ninjas, and then starts trash talking the rest.
The original Turtles calling the Utrom Shredder a coward.
And also, the Shredder gets one when he threatens Splinter, as well as using the Turtles to find "Turtle Prime", but, before he explains this, he does a Title Drop, that's right, the Big Bad was given the honor to do a Title Drop.
Made better when you realize Bebop and Rocksteady saved the multiverse.
A minor one, but this troper was rather glad to see the '87 Shredder finally get fed up and attack Krang for all the insults he dishes out.
The moment that just made me go Hell Yeah was after the 2k3 Turtles told the 1987 Turtles there was no guarantee that they were going to make it out alive. Faced with the prospect of losing their lives for the first time, Leonardo says "Let's do this!" and they all put their hands in together.
When the 1987 and 2003 Turtles declare each other "brothers" before going to face the 2003 Shredder. By extension, the Mirage Turtles calling their two sets of counterparts bros at the end of the movie.
The movie's revelation that every incarnation of the TMNT franchise ever is connected to the same multiverse, complete with a slideshow of all versions of the TMNT in all media.
The Mirage Turtles plastering themselves against the giant Shredder's visor. At that moment the Shredder knew fear like never before.
I think you mean to say "Knew fear for the first time."
Bishop vs. everyone fight in the episode "Hun on the Run". Watching Bishop use anything he can get his hands on as a weapon—including his glasses and necktie— is a thing of beauty.
Hun himself was pretty awesome in that episode as well, he busts into Bishop's underground base with a tank-like vehicle and pretty much sends Bishop's Mooks running for their lives, and he puts up a pretty decent fight against Bishop himself.
Leo's finishing off Hun in "The Shredder Strikes". I could try to describe Leo's jump-kicking here, but words wouldn't suffice.
Mikey of all people winning the Battle Nexus Tournament.
His battle against Raphael was especially memorable and awesome, due tot he fact that Mikey never even has to throw a single punch, kick or any attack. Mikey defeats him simply by annoying him into a fit of rage and dodging his attacks, essentially making Raph defeat himself.
The final battle against the Tengu Shredder in the Lost Season. We have almost all characters (including some of the villains) teaming up against the evil forces of the Tengu Shredder. The Shredder and Turtles change into dragons, have a large battle in the skies. And then even the spirit of Hamato Yoshi appears and cuts the shredder IN HALF VERTICALLY! ON A 4KIDS CARTOON! Granted, he wasnt human anymore. But still, his death was one of the few thats explicitly shown.
His appearances may be few, but everytime Miyamoto Usagi from Usagi Yojimbo appeared, he made those episodes count. Special props to both him and Leo when the latter ends up in his world and they fight to save Usagi's friends..
Everything involving Bishop. EVERYTHING. He's probably the most competent non-mystical fighter in the series. Sure, he's got super strength, but that's pretty much it. He goes up against multiple armed ninja masters with his bare hands or an Improvised Weapon and uses skill and pragmatism to come out of the battle with something that benefits him. Plus, who can resist that nice suit of his?
The entire episode of The Christmas Aliens was one huge crowning moment of awesome and heartwarming for Mikey. In a nutshell, some Purple Dragons steal a truck full of toys meant for orphans to make some easy money, Mikey takes them out, hijacks the truck for himself, and uses it to defend himself from more Purple Dragons while simultaneously evading the police who've mistaken him for a Purple Dragon all while keeping his new friend safe, returns home to convince his family and their party guests to move the party to the orphanage and succssfully delivers the toys to the orphans. Oh yeah, and he does all this without his nunchucks.
Raph and his new friend Tyler get one in Lone Raph and Cub. Raph is capable of handling the mobsters without breaking a single sweat, until one of them blinds him. With some help from Tyler, he manages to take down the mob boss.
Splinter, April, and Casey infiltrating Bishop's lab to rescue the turtles all while two evil alien races are fighting each other. Noteworthy in that Splinter had to teach April and Casey the same ninjitsu techniques that took the turtles 15 years to learn within minutes.
Splinter: The way of invisibility takes a lifetime to master, circumstances however, require us to learn as we go.