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.
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.
From the cartoons
"The Great Gladiator Gig" has plenty of funny conversations:
Bowser: Guess who's coming to dinner, Tryclydius — the Marios! Tryclyde:Mash 'em! Stump 'em! Crush 'em! Bowser: Don't let 'em see you, snake-breath. I want 'em to walk into my trap. Tryclyde: Mash 'em! Stump 'em! Crush 'em! Bowser: Why do I have to give you an order three times before it sinks in!? Tryclyde heads: I don't know, ask him. / I don't know, ask him.
"Uh, excuse my brother, he gets nervous around guys six times bigger than him!"
Mario: This is some place, hey Luigi? Luigi: It's some place, but I don't know what place. Brutius: This is the place where we capture you! Mario: Oh. See, Luigi? This is the place where they— Mario and Luigi:Capture us!?
"Wait a macaroni minute! I got an idea! Dance, Luigi!" "You lost your noodle!?"
"Princess, I Shrunk the Marios":
Bowser: Know what I'm gonna do with you buttinskis? Mario: Say you're sorry and let us go?
"Send in the Clown":
Bowser: A circus isn't a circus without a dinosaur-taming act! Mario: Uh, how about a chipmunk-taming act instead?
"King Mario of Cramalot":
Bowser: So, Mario thinks he's king of Cramalot. That impudent little faucet-fixer! How dare he! There's only one king of Cramalot! And who is that? Koopa Troopa: Ahh, can ya give me a hint? Bowser: He's sitting right here on this throne! Koopa Troopa: Well gee, maybe ya better get off him.
Mario: Luigi, you have to swim across the moat and lower the drawbridge.
Luigi: ME? B-b-but, I can't! I'm gonna have a baby! (pretends to moan in pain)
Bowser praising himself in "Brooklyn Bound":
"The courage beyond compare, the bravery beyond description, I praise this great hero, the superior fiend... me, Koopa Khan the magnificent! If I didn't deserve this, I wouldn't give it to me."
There's also this brief scene where Koopa is ordering some pizza for delivery. Later on, when he's confronting the Mario Bros. at the climax, a voice on his walky-talky says, "Sir, your pizza is here!" "Not now."
Mario and Luigi having their mugshots taken.
Mario: Are we dead?
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!