* The confrontation between Bowser and Donkey Kong; Bowser has a gun that transforms the characters intro trophies. Diddy Kong doesn't understand the danger he's in, so Donkey Kong performs a HeroicSacrifice by knocking Diddy into the air TakingTheBullet Bowser aimed for Diddy, transforming him into a trophy, all to protect his buddy. Aw!
* The friendship that forms between Samus and Pikachu is sweet. Samus is the "I work alone" type, and since she's human and Pikachu is a Pokemon, it makes her look like Pikachu's trainer.
** Especially her face when she sees Pikachu being basically tortured in the machine. She takes in about a ''second'' of seeing the little guy squealing in pain and promptly responds with a non-verbal HELL NO and smashes the glass.
* When Ness realizes the Dedede badges that revived him and Luigi belong to Dedede, he immediately decides to revive him. This for some guy he doesn't even know!
** On that note, there's also Ness and Luigi helping Dedede up after Wario attacks him. This doubles as a [=CMoF=] on Wario's part.
* Ness again, he jumps in to save a kid he just met. Then he pushes him out of harms way not knowing if he'll be revived or not! Ness is a real sweet kid.
* Whichever scene you play ("Mario's Misunderstanding/Link's Misunderstanding") is kind of heartwarming in a way. Mario gets it if he sees his princess's trophy apparently dissolve at the hands of Link, and rushes in to try and avenge her. Whereas if you play Link, he's the one charging at Mario, who then has to avoid becoming a plumber-kebab. Either way, it's nice to know how much they both care.
* Dedede! Boy was he a surprise! First he [[spoiler:gathers up as many heroes as he can in one place to make a hero team. Then he gives up the one thing he knows can revive trophies for one of the princesses. Near the end of the game he gives Kirby a BearHug!]]
* The friendship between Pokemon Trainer and Lucas, particularly their handshake after [[spoiler:Lucas's Crowning Moment of Awesome blowing up Galleom's arm to save himself and PT.]]
* After defeating Tabuu, you see the entire playable cast (or at least, all those you saved) on a cliff, overlooking the ocean where the Great Maze area of Subspace was, with the main theme blaring full blast. Then, the credits cut in, with an epic medley of the credits theme of the original Smash Bros, the main theme of Melee, and a piano solo of the main theme from Brawl, all while bits of cutscenes that correspond to the mood of the music play in a little box on the screen.
** The music is great, and now knowing the lyrics, its meaning is clear.
---> "Now, my friends are here with me. [[EnemyMine Some once heroes, some my mortal enemies]]. And now, as we face each other in battle, locked in combat, we shine ever brighter."
* The fact Diddy Kong forces Fox and Falco to help save his friend Donkey Kong is sweet. For Donkey Kong, at least.
** The fact that neither of the protest much indicates that they really don't mind helping. Falco's thumb's-up to Diddy is proof of that.
* Mega Man finally showing up in the series, because many fans asked for him, so they gave the fans what they wanted.
** Keiji Inafune, often called "the father of Mega Man", stated that he was "ecstatic" that Mega Man was added to the roster. He also said that he was looking forward to playing as Mega Man and beating his own kids in the game.
* As a secret unlockable character, Luigi usually isn't revealed until after the game is released. However, seeing as how it's [[TheYearOfLuigi The Year of Luigi]], they decided to give the man in green the spotlight for Super Smash Bros. 4 early, further showing that Nintendo hasn't forgotten about [[StuckInTheirShadow Mario's younger brother]].