Mario: Whoops! First Lady: Oh, Mario! I don't mean to complain, Mario, but my husband can't run the country from up here!
To infiltrate in the Doomship, Mario and Luigi wear obviously fake Hammer Bros armor when Luigi expresses doubt in that plan Mario reasures him "You're my own brother and even I don't recognize you" as soon as they're on board...
Sledge Bro: Putting on a little weight, aren't you Mario?
"Toddler Terrors of Time Travel": Koopa sucking his thumb even after Kooky turns him back into an adult.
Plus the scene where Koopa and Kooky pose as plumbers to fix a lady's bathroom drain, when they actually plan to clog it.
Woman: Um, how are you doing in there, costumed plumbers?
Koopa: Aww shut yer trap!
Woman: Gracious! How rude! I thought you made plumbing a party!
In "Princess Toadstool For President," the Princess ends up winning by a vote of six million, four hundred and thirty six thousand to one. Not only is this an amazing number, it means even the Koopalings voted for her over King Koopa!
King Koopa: How could I be the only one to vote for me?
Cheatsy: We couldn't help it, King Dad! She's so nice, and you're so...
King Koopa:(Growls angrily)
Cheatsy: Right, that!
Also, anytime Koopa acts sickeningly nice in the same episode.
This exchange between Princess Toadstool and Toad in Up, Up, and a Koopa.