* Smoldergeist makes constant threats about how you'll never make it past the TutorialLevel. One piece of dialogue reveals Peach, who you're chasing after, is easily getting past them too!
* The way you [[spoiler: initiate the last Giant Luigi boss battle.]] Usually, triggering Giant Luigi requires him to be in a dire situation, and in a state of severe panic. [[spoiler: In the battle versus Giant Bowser, Luigi pulls the cap over his eyes and smirks with confidence. Mario is momentarily surprised by his brother's confidence but they both clasp hands and Dreamy Luigi grows with the words in the background saying things like "Do my best!" and "My big bro!"]] It's pretty heart-warming too at that point.
* [[spoiler: Bowser pulling a HijackedByGanon moment, usually he is on the receiving end. This time he tricks the villain, instead of the villain tricking him.]]
** It's not just that [[spoiler: Bowser managed to usurp power. Rather, it's that it is ''heavily'' implied that he was playing Antasma the ''entire time''. He simply pretended to be TheDragon in order to wring all he could out of Antasma, and boot him aside when it was clear there was no more to gain. The key props here is that Bowser was' well aware Antasma would perceive his bluster and ego as ignorance. Say what you will about Bowser, he is 'not'' as idiotic as he appears to be and is still the formidable villain he's always been.]]
** Other, more sympathetic people maydirect more of their attention towards Antasma, given that it appeared that he had no intention to ever betray Bowser, and that they would legitimately be working as a team.
* '''Finishing Bros'''. It's the move used to end Giant Luigi battles, and it involves ''[[spoiler: Luigi jumping into space and grabbing a star, with Mario jumping on the star and flying it down into the boss's heart]]''.
** [[spoiler: '''Star Driver'''. In the final Giant Luigi battle, Kamek uses his magic to make Giant Bowser grow to truly colossal size. The heroes' answer? Initiate Finishing Bros, with Prince Dreambert using his power to make the star itself grow gigantic, turning the attack into the aforementioned one. Luigi throws the giant star with Mario on it at Bowser, who tries shooting it down with a barrage of fireballs. [[BestBossEver You have to control Mario and the star by tilting the 3DS to avoid the barrage]], finally striking him head on and [[OneHitKill finishing him off instantly.]]]]
* The Final Boss. [[spoiler:As said above, Bowser betrays Antasma before Antasma has a chance to do the same. Then he takes the Dream Stone, and prepares to wish Mario and Luigi away. Peach and Starlow shatter the stone first... and then Bowser inhales the fragments, doubles in size, starts glowing like he grabbed a Starman, and becomes one of the most awesome final boss battles ever. His transformation looks awesome, the fight is awesome, and you will ''feel'' awesome when you win.]]
** [[spoiler:The music helps too. Yes, that's right, '''Bowser''' gets an incredibly epic, intense and emotional ''VideoGame/KingdomHearts''-esque final battle theme that many argue is one of his best yet and one of composer Yoko Shimomura's finest works.]]
** [[spoiler:There's also a moment during the battle in which Dreamy Bowser summons an airship to chase after Luigi you see Mario's face ticked before it starts chasing Luigi and while Luigi avoids the ship's ammo, Mario goes on the airship smacking the shy guys away and smashing that ship until it either flies away (Mario giving that ticked look again) or ultimately destroys it. That just shows how dedicated Mario is to protecting his brother from harm.]]
** A big one for the Mario Brothers in this battle - This time, they ''don't have any help'' (apart from a health restore). They take on a RealityWarper, and win, all on their own. ''This'' is what they're truly capable of.
* The mere fact that Bowser actually manages to [[spoiler:remember Luigi's name, implying that Luigi is finally considered a Worthy Opponent in Bowser's eyes.]]
--> Bowser: I'LL BE BACK! '''MARIO!''' GREEN 'STA--[[spoiler: I MEAN, '''LUIGI'''!]]
* [[spoiler:Giant Luigi vs Giant Bowser.]] It's easily the best giant boss in the series, made better by the fact you're actually taking down [[spoiler:Bowser's dream self]], so in other words basically countering his ultimate wish fulfillment. About six or seven phases of attacks, tons of clever ways to counter attacks, a surprise twist finale at the end, great music, and much more make it a fantastic battle, albeit a difficult one.
** The final phase has easily the most absurd and actually frightening concept you could think of in a ''Mario'' game. See, [[spoiler:Bowser can grow giant by himself, thanks to what the Bros. did last game. Kamek used to do that--still can. Even after Bowser is ''already'' giant. Three words, people: '''''Giant''... Giant... Bowser.''']]
** To say nothing of the battle's prelude. [[spoiler:While Bowser's giant form startles the Bros. at first, they respond calmly to this threat after numerous other ones and prepare for their final one. While Luigi's giant form had been triggered by a cowering Luigi pulling his hat over his eyes previously, he ''deliberately sets the transformation off this time''. Even Starlow cannot help but note how confident he looks this time around.]]
** If you think about it, the fact that [[spoiler:Bowser goes giant at all is a Moment of Awesome for the Mario Bros.]] In ''Bowser's Inside Story'', [[spoiler:Bowser only ever had to become giant to deal with threats like a train, a tower, and ''entire castles''. It's telling of just how much Bowser fears the Mario Bros. that he willingly jumps to his death to unleash his giant form, '''''while he's in his dream''''', just so that he can crush the Mario Bros.]]
* A particular moment in the BonusBoss fight. [[spoiler:Bowser Jr]] starts out the fight in the [[spoiler:Koopa Clown Car]], but will eventually get out. You can then jump in, and start one of the game's many "chase attack" segments... but this time, ''the Mario Bros'' are the ones on the offensive!
** [[spoiler:He uses the Border Jump minigame from ''Superstar Saga'' as an attack.]] Talk about nostalgia...
*** [[spoiler:[[ThatOneAttack Or teeth-clenching rage]], [[ScrappyMechanic as not a lot of people remember the Border Jump fondly...]]]]
** Let's be honest and say [[BestBossEver the entire Bonus Boss fight is one of the greatest fights in the series.]]
* A more subtle one: Right before Earthwake attacks, Pi'illoper tells the bros how strong and horrifying it is... and also mentions the word gigantic. During the conversation, Mario looks back at Luigi... who simply nods, realizing what will happen and bravely accepting the challenge.
* In the scene right before the final battle, [[spoiler:Bowser starts using the Dream Stone and gloats about how he'll destroy the Bros., when Peach and Starlow use Wish Power to just stop him in his tracks and destroy the Dream Stone! Sure, Bowser just swallows the Dream Stone shards, but when you think of it, this means that Peach and Starlow's Wish Power is more powerful than the Dream Stone!]]
** Also doubles as a nice CallBack to the previous game when the two of them also double-teamed him at the beginning of the game to kick him out of Peach's Castle.
* And you have to give Antasma this. [[spoiler:Bowser's double-crossed him. His plans have been practically flushed down the toilet in one clawing stroke. He could've taken the opportunity to run, but he doesn't. Instead he stands his ground and challenges Dreambert to a duel, the two proving to be equally match. Their fight then moves to the Dream World where Antasma, who's powers are greatly amplified, [[CurbStompBattle curb stomps]] him. When Mario steps in to fight in his place, Antasma buckles down and fights the plumber with everything he has. Yes, he lost like all of Mario's adversaries, but you can't say he didn't go out fighting.]]
** I'm not sure why, but there's something awesome about [[spoiler: Prince Dreambert during the battle with Antasma. Sure, he doesn't do anything except heal Mario a small amount every turn, but the look on his face shows that he's done with Antasma's shit and that he's going to support Mario all the way.]]
* Popple, while still a funny and interesting character, TookALevelInJerkass here. He forbids the bros to pass an area they need to pass since he mistakes a peaceful Wiggler for a security guard, forces them to fight the Wiggler with him, and is not only useless in the Wiggler fight, but a ''hindrance''. And then he betrays them. What follows is probably the second greatest example of CatharsisFactor in the game, as Popple is much easier than the Wiggler.
** It gets better. Occasionally you can target Popple ''before'' he officially becomes an enemy, in order to stop him from aggravating the Wiggler into using a stronger attack. Cue players [[ThereIsNoKillLikeOverkill unleashing their strongest Bros. Attacks on Popple]] just to vent their frustration with him.