In Episode 30, Yami gives Arkana an awesome Shut Up, Hannibal! which is even better than the original line from the show.
Arkana: You know, Yugi, there's an old saying among high-rollers and card sharks: "Always trust your opponents, but only after you've cut their decks." Yami (original): Here's another saying: "Never trust a masked man." Yami (abridged): Yeah, well here's another saying: "Go [BLEEP] yourself, Arkana."
In Episode 31, while admittedly it happened off-camera (if at all), Serenity convincing the kid that thought he was Ash that he had cancer was pretty awesome, as it got him to finally shut up.
The ending also applies:
Joey: Let that be a lesson to you—minor characters from season 1 stand no chance in this tournament. That's why I'm gonna take you out, one at a time! Because I'm Joey Wheeler: Card Game Warrior! Weevil: Would you like to see my bunghole? Joey: Okay, Tristan, now you can break his neck. Weevil: (head twisting sharply to the right) AGH! (Weevil falls over. Cut over to Tristan, standing several yards off.) Tristan: (casually) Yeah, I can break necks with my mind.
Episode 32 ending with Marik getting on his motorcycle and tear-assing around Domino City, set to "More than a Feeling".
Grandpa Moto: Shut up, Mokuba— Mokuba: NO, YOU SHUT UP! (Grandpa Moto and Téa look at him in utter shock)
With his life on the line, Yugi manages to give Joey the strongest, most heartfelt friendship speech he can muster. Doubly awesome when you remember how annoying it is when Téa does it.
This exchange from Episode 40 is so cold it becomes awesome.
Yami: "Hey, Bakura! Any last words before Slifer toasts your ass?"
Bakura: "I want my mommy "
Yami: "That'll work."
In Episode 43:
Joey: "Melvin, you son of a bitch. You stay away from Mai, or I'll—"
Melvin: * pulls a lightsaber out of his Millenium Rod* "You really have no clue what you're *** ing with here, do you?"
Joey: "Uh yeah, I'll just be getting out of the way now."
Melvin: "That's what I thought."
And one for Mai that she didn't get in the original anime; making Melvin forget about Mr. Tweetums.
Ishizu Ishtar shuts Kaiba up mid-rant about how awesome he is to turn his entire strategy on its head. Kaiba, generally the calmest character, flips out and drops a huge F-bomb extended over several scenes.
Note that we're talking about the same character who maybe 30 seconds earlier told Ishizu to, and I quote, "Put up your f*cking dukes, bitch! 'Cause you're going down, Kaiba Corp-style!"
The only uncensored f-bomb in the series, at that. Not counting the "I'm on a Blimp" video.
Especially the Marik/Florence "Stand by Me" duet. Could probably be a Heartwarming Moment, too.
Joey's speech from Episode 50, after being accused by Johnson of Team 4Kids of copyright infringement:
Joey: Yeah, I have a closing statement. Maybe we have committed copyright infringement. But you gotta know we've done everything in our power to support the Yu-Gi-Oh franchise! And if it weren't for us, I don't think the show would be nearly as strong as it is right now!
Johnson: And where is your evidence of such?
Joey: Look around, Johnson! There are more Yu-Gi-Oh fans now than ever before! And the more you try to stifle our creativity, the more we'll try to express our love for a show that's about more than children's card games! It's about fighting for what you believe in, and I believe in this show and its fans now more than ever! Because they believe in me!
Yugi: This is so meta.
Joey: Flame Swordsman! Use the strength given to me by the Yu-Gi-Oh fanbase to wipe out his life points!
Flame Swordsman: My name... is... FRANK!! [commences to pwn Johnson's Deck Master]
Ironman playing when Mecha Nezbit first appears.
Tristan's pre-death speech (doubles as a Crowning Moment of Funny at points)
Tristan: It's okay Serenity, I lived my life as a side character, fit only for spouting mindless quips and catchphrases. But now, I get to die the way I always wanted, falling, screaming like a girl into a pit of boiling hot lava, flesh being seared from my bones. If I do survive, I'd probably be unrecognizable. But if I do die, It'll be as a main character.
Episode 53: By this point, its almost time for the big 5's final duel, but due to a little bit of editing, Téa's currently possessed by the Penguin-obsessed member of The Big 5. However, in the pre-opening part of the episode, after witnessing the guy fail at being Téa, the part of Marik that possessed Téa speaks up and, after a quick conversation, literally kicks the guy out. Let me say that again. Marik's spirit, without the rod, managed to kick out another spirit who had taken over a body he only possess occasionally.
Melvin tells Ishizu that he's sending everyone to the shadow realm, saving her for last. Why? Because shut up. His cold delivery sells it.
Episode 57: Joey has Gearfried attack Kaiba's life points, putting him ahead of him to duel with Melvin. One of the few times he's gained a victory over the smug son of a bitch, and taunts him about it.
Joey: Hey, Kaiba, how's the weather up there? Kaiba:(spits on his cheek) It's raining.
Well, he got spat in the face for his troubles, but still
The We Will Rock You parody in Episode 59. Plus Yami winning against Kaiba for the gajillionth time.
Kaiba gets one in episode 60: when confronted on his anger by Mokuba and the notion he considers the others friends, he calls Duke, Joey, and Tristan out on their failings in spectacular fashion.
Even though Raphael's motives are not the best in the world he did manage to catch Yami off guard by actually dueling him this time instead of standing around conversing with him. For someone who could only say "ZUG ZUG" for a while, that's pretty impressive.
There's also him actually beating Yami, a feat that, so far, has only been shared by three others: Pegasus in his pre-Duelist Kingdom duel with Yami, Kaiba in his first rematch against him, and Joey after the Battle City finals. Bonus points for not resorting to stalling for time or reading his mind like Pegasus, or outright threatening to get himself killed like Kaiba (unless you count the Seal of Orichalcos, but then again it's basically a discount Shadow Game anyway).
LittleKuriboh's performance as Yami in Episode 71 after he uses the Seal of Orichalcos shows that when he can be evil, he can legitimately make the people who forced him into that position rethink that choice.
Raphael: Now do you see how right I was about being evil?
Yami: Yes, Raphael. I see exactly what you mean. And now that I know how evil I can be, I am going to destroy you and everything you hold dear and bathe in the afterglow of your demise. HAHAHAHAHAHAHA!!!!
Yami: Look at you, being all defiant. It's cute. But once I've assembled all my monsters, I'll hurl them at you with my Catapult Turtle in a wave of deadly precision. And as you just finished telling me, a wave is all it takes to break you. It's time to d-d-d-d-d-die. Any final words?
In Episode 73, LittleKuriboh finally gets to do his take on Yami overkilling Weevil. Yes, he dubs the memeticallyhamtastic "DORO! MONSUTAA KAADO!" from the original anime wholesale. In the DAN GREEN Yami voice. And it is glorious.
As was the case in Episode 71 above, LittleKuriboh's performance as Yami is compelling in how it continues to play his rage and sadness at losing Yugi straight. It makes his rage at Weevil all the more chilling.
Tea: Pharaoh! Don't antagonize him!
Yami: (jokingly) Come on, Tea! It's Weevil! What's the worst he could -
Weevil: (rips up card he'd led Yami to believe contained Yugi's soul)
In that same episode, Joey manages to completely No-Sell Rex and delivers likely the best burn he's ever gotten in the whole show:
Joey: "A dog peed on you! *laughs* Come on Rex, you should be proud! That was the first genuine laugh your character has produced on this show!"
It has to be said that after 72 episodes of just doing Beavis and Butthead, the Orichalcos retcon lets LittleKuriboh show off a truly amazing Jimmy Zoppi impression. Seriously, listen to Weevil's voice in the 4kids dub, then listen to it here.
Episode 76, Valon donning holographic armor parts right before going One Punch Man on the giant Diamond Head Dragon qualifies. He even lampshades this, saying "This card's special effect allows me to - oh, who am I kidding? It makes me look really bonkers cool while I kick the shit out of you!" For bonus badassery, he yells "Anime Trope Achieved!"
Episode 77, Alister sends Kaiba in a flashback to confront him with the horror of war and make him have an epiphany about how humanity deserves to be wiped out. Not only does Kaiba manage to fight his way out of the flashback, the experience has the opposite effects on him, as he decides humanity deserves to be saved, if just because they made something as awesome as a dragon tank.
Joey and Valon's mech armor duel in episode 79, especially so with "Fang of Critias" playing in the background.
Valon: Joey's just become the single most badass character in Yugioh! Nothing makes any sense any more!
Joey: Gundam RAAAGE!!
When Raphael sacrifices all of his monsters to power Guardian Deathscythe, Yami epically calls him out on his hypocrisy after Raphael previously called Yami a monster for sacrificing his monsters during their first duel.
Also from Episode 80: This episode features the word fuck but for the first time it isn't bleeped or stretched out for once!
Dartz: Look at youwself! Look at everything you've dooone! You got a second chance at wahf! Oh! And how do you choose to spend it? Beating people in games y'already good at, and telling them how much they soock. Yami: It's not my fault if they refuse to git gud. Dartz: I know you're wight, but what is your fauwt is the way you take your fwends for gwanted or, oh, oh, do you even think of them as your fwewends? Yami: Of course I— Dartz: Oh, right, you can't even defend yoursewf! Not once have you taken the tahm to appweciate everything they've done for you, how patient dey' been. You're too busy calling Twistan stupaad, or Téa a slooot, or insulting the person whose body you now inhabit. Yami: Yugi... Dartz: Aww, that's the truth, though, Phawowoaoh. No Orichalcamalos magic, no bullshit powers. You're no hewo. You don't even deserve those fwends you surround yourself with. And you certainly don't deserve to keep wiving in Yugaay Muh-to's body. Just give it up. It's easier than fightin' the twuth.
Yami rejects this speech with his belief in The Power of Friendship, and this moment is punctuated with the 4Kids Yu-Gi-Oh! theme.
Serious props should go to Takahata, who, even when doing Dartz's exaggerated accent, manages to deliver the entire speech with absolute sincerity.
Dartz gets a sick one-liner in the climax of the duel.
Dartz: But you know what sinks ships, Phawowoah? Canon.
Also crosses a bit into Heartwarming. Despite all their bickering, they're basically each acknowledging the other two as worthy of beig Yu-Gi-Oh! protagonists (even Jaden).
Admit it, the parody opening in Doctor Who style for the crossover abridge movie was freaking awesome!
In the movie, we have Yami Yugi doing what he does best to take down Paradox...screwing the rules.
Yami: So stand back y'all, cause it's time for a real main character to take the field.
Paradox: Oh pwease, you may be the King of Games in your timewine, but where I come from duel monsters has evolved far beyond your understanding. Compared to me you are just a learner.
Yami: That may be the case in your timeline Paradox, but then we're not in your timeline, are we?
Yami: And where I come from, duel monsters is still a broken, exploitable mess of a game. And I'm about to exploit the hell out of it! (summons Dark Magician and Dark Magician With Big Boobies and destroys his Malefic Paradox Dragon)
Yami: I believe the appropriate phrase is, 'Boo-yah'.
YGOTAS Sails Away. Almost every character gets a part, and some are actually pretty good singers (Tristan). And it. Is. EPIC.
In the maybe-canon spinoff fanfic Marik & Bakura Go To Censored Town, Ryou Bakura, of ALL PEOPLE, has one of these, when he convinces Florence to go back and apologise to Marik, making Florence realise that Marik is the only real friend that he has. To do this, he actually takes control of one of his arms so that he can force Florence to look at a photo he had of Marik. Considering that he hadn't even been mentioned in the fic up to that point, and how he's been pretty much ignored for most of the Abridged series, it was pretty awesome.
Ryou: If I were in your place, I would rather die than lose any of my friends. Especially one that means as much to you as him.
In the first episode of Season Zero, the way Yami convinces Yugi to finish the Millenium Puzzle, takes over his body (Which was also kind of creepy, but in a cool way), and then kills Ushio in, what one would say, the most epic moment in the show.
Yami: Garbage day!
Ushio: Yugi! What are you doing?
Yami: Ushio, baby! How's it hanging? Get it? 'Cause you're gonna die! Hehe...
Yami: Guess you had be there...
Ushio: So... are you gonna give me the money now?
Yami: Tell you what... (Slides down building as rock plays in the background, sliding playing cards along the way, stops right in front of Ushio, hanging by a rope) Hi.
Yami: Wanna Play a game?
Ushio: ..What kinda game?
Yami: Whoever dies first loses!
Yami:(Holds up a playing card) Look, the Queen of Spades!
Ushio: ...What does that d-
Yami: You lose! (Lets go of rope holding Ushio, dropping him into a lake of man-eating Worms) Hope ya like Man-eating Worms!
Ushio: huh, I wonder what he meant by tha- (Notices Giant Worms) OH MY GOD THAT IS WHAT HE MEANT BY THAT!
During the absolutely hilarious "Michael Bay's Yu-Gi-Oh", Yami appears, criticizes all of the ridiculousness around him, points out plot holes, and pretty much explains WHY Michael Bay movies don't work. Then asks why we can't have a loyal adaptation of a much-loved show from Hollywood. Awesome.