Fawful: I am the great Cackletta's most best pupil, who is called Fawful. I am here, laughing at you. If you are giving us the chase, then you are idiots of foolishness!...
One of the funniest scenes in Superstar Saga was his "comeback speech" with Peasley:
Fawful: "Hah! Now taste the finale, when carelessness opens the door to a comeback not expected by you! Your lives that I spit on are now but a caricature of a cartoon drawn by a kid who is stupid! You shall all fall and vanish with your precious Beanbean Kingdom as I laugh heartily at you!"
Peasley: *slashes Fawful* "HAH! In the finale of the finale, when negligence begets rashness, the comeback is comeback-upon!"
Fawful: *shocks Peasley* "I HAVE FURY!! In the last moments of the finale of the finale, when relief leads to negligence that begets rashness... That is when the comeback that faltered comes back and beats your pathetic comeback that I scoff at!"
He's the Big Bad in Bowser's Inside Story. Seeing him singing the Scooby Doo theme while he's looking for the Dark Star is simply priceless, but he has dozens of hilarious moments. "I HAVE SUCTION" is the best line any evil villain will ever say before draining the evil power from an Artifact of Doom.
Fawful: Fawfully-doo!♪ Where are you?! ♪Dark Star, needing you!♪
His calling Bowser "the king of stupid" — though Bowser certainly does make some incredibly stupid decisions throughout most of the game...
Bowser himself gets one where he gets hit by a train and crashed through several boulders. Through sheer brute strength, he very nearly stops the thing... Until he trips over a pebble. The last thing he says before he gets crushed?
Bowser: ... Doh.
The scene where the Mario Bros. fix Bowser's back qualifies. Toadsworth invites Toadbert to have a cup of tea as the impulse triggered by the Bros. is going to work its slooooow magic. After they constantly rub it in the player's face, the message "Why not put the DS system down and take a short tea break?" pops up and the player is supposed to simply wait until the alarm rings. Unless they have a code.
You've also got the mind-controlled Hammer Bros. in Partners In Time, which speak in leet.
WE R TEH SHROOB ALLIES. WE ROXOR U AND THEN ROFL. THEN U AM CRY.
Yoshi's Island: You're heading towards the boss of World 3, the Naval Piranha Plant. You get into the room, close enough to hop up on the ledge, and you can even see the little bugger that'll get transformed... but the cutscene hasn't cued up yet. Well, maybe you'll just take a quick cheap-shot with an egg for laughs...
Kamek: OH MY!!
Piranha Plant: ***EXPLODES***
Not to mention the look on Yoshi's face before Prince Froggy eats him and after shitting him out of his stomach. Yoshi goes from "O_o" to ":3" in seconds flat!
In the later Mario Party titles, games played in 2-on-2 Team Mode started getting "team names" handed to them depending on which characters were in the team. While some of them were predictable for obvious character combinations (like Luigi and Yoshi being called "Green Machines"), sticking together any really weird combination of characters results in weird and often hilarious team names:
There's some in the actual intro as well, such as the Mario Bros. watching Bowser's Bob-Omb-packed vehicle descend towards the ground. "Oh, this looks bad..."
In Mario Golf: Toadstool Tour, when Waluigi gets an eagle or better, he does a dance routine that ends with a lengthy spin followed by a pose where he holds the brim of his hat and points at the camera with an audible sound effect. After a beat, he realizes he's pointing in the wrong direction.
He does it again in Mario Super Sluggers. Most character introductions show them boasting or preparing to hit the ball. Waluigi enters, shouting WAAAAAALUIGI and preparing to hit the ball, only to realize he is facing the player. He makes a "i meant to do that" gesture to the player and switches to the right side.
In Superstars Baseball, Boswer gets a platinum one when you decide to not face Mario in Bowser mode at the final boss battle.
Bowser: NO! Remember your blood sugar Bowser. Ok, now go wash your hands...
In Super Mario Bros. 3 if you complete a level as Tanooki Mario, the Toad next to the restored King says "Thank you, kind raccoon. Please tell me your name." As if the exposed face of a mustached Italian man wasn't enough of a hint as to who you are.
If you finish any of the Koopalings in a suit (Frog, Hammer, Tanooki) the restored King will have a different dialog depending on the suit.
Toad: Being imprisoned in these walls can drive a fungus crazy. When I really start to freak out, I think to myself, "Well, I'm going to be here for a while, so I might as well stare at the fish. They are oddly hypnotic." Then I actually start to like being captured............Aaaguugh! IT'S MADNESS! I've got to snap out of this! You have to free us before we're all completely brainwashed! ...But for now, why don't you gaze at the fish with me. You look tense. Come relax.
During the end credits of Super Mario 3D World, Bowser gets his just desserts by being trapped in a bottle, helplessly tapping against the glass.
What Tuxie says in Super Mario 64 DS when Yoshi puts her in his mouth.
Similarly, when Yoshi eats a rabbit he's already captured.
Rabbit: What part of "I'm not your lunch" do you not understand? I already gave you the key! Put me down! (rabbit is spat out) I'm not chow. How many many times do I have to tell you that? I know I'm irresistibly cute, but try to restrain yourself!
The Gearmos in Super Mario Galaxy and it's sequel. Special mention goes to the one at the end of the first game's Battlerock Galaxy's purple coin mission, particularly if you get absolutely ZERO purple coins:
Gearmo: You got zero. ZERO PURPLE COINS! Tell me you're doing that on purpose! This old iron lady isn't amused.
Similarly, there's also one in the Buoy Base Galaxy that gets mad when you break the floating fortress' weight:
Gearmo: You destroyed the weight! So you just go around breaking stuff, eh?! You think that's OK? Breaking stuff?
There's also the Gearmo from the Chompworks Galaxy second mission (Spring into the Chompworks) in the second game, who is repeatedly hit by rolling Chomps:
Gearmo: BRING IT ON! Gimme your worst!
From the movie
Iggy and Spike's stupidity.
Spike: We were wrong again. How many times have we got this wrong? Iggy:You've gotten it wrong five times. Spike: 0 for five. 0 for five. What percent is that? Iggy: I dunno. Let me think. [pause] Iggy: I dunno. But it's not good.
Later, they mistake Daniella for Daisy.
Spike: I'm gonna get the girl. Iggy: That's not the girl. Spike: Yeah it is, she's wearing a disguise. I could spot her a mile away. Iggy: Of course she's wearing a disguise. She thinks she can fool us.
Gotta love the Troopas dancing to that elevator music.
It's even funnier when their commander catches them at it.
Later, Toad is able to distract them by playing the same song on his harmonica.
Hopper's deadpan delivery as he spins a globe of the alternate dimension, showing that aside from Dinohattan, it's all a giant wasteland. No wonder he wants to break into the human world.
"Ruler of all that you see. A few miserable streets, and... an endless desert."
Koopa has Iggy and Spike put into the Devo Chamber to evolve them and make them smarter... and when they pop out of it looking exactly the same, his stare of utter confusion is priceless. The rest of the scene is pretty good as the two suddenly demonstrate their new intelligence by indulging in Sesquipedalian Loquaciousness.
Koopa: Both of you, go to the desert! Iggy: Excuse me, excuse me. That hardly seems logical, does it? Perhaps we should stay here and formulate our own strategy. Tete-tete, inner circle, that sort of thing. King Koopa: Here's what's logical to me — If you do not return with the plumbers and the rock... I shall personally, kill you. Iggy: We're going. Spike: After you.
Mario and Luigi are hopelessly lost in the Koopahari Desert and they argue along the way.
Mario: You said the tunnel. Luigi: I did not, I said parkway! Mario: But you meant the tunnel! Go on, pick a direction! Any direction you like! Luigi:(hits Mario's head) Na na na na na! Mario: Hey, that looks good over there! (pointing at quicksand) That's it, let's die there!
This dialogue, while Mario and Luigi are hopelessly lost in Dinohattan.
Luigi: Excuse me, miss. Can you tell me where I am? Woman: Yeah, you're in my way! (pushed them away) Egg-suckers! Mario: Who are these people?!
Daniella shouting "Hey, Mario!" as he's attempting to break the girls out silently.