User blog comment:KirbiMiroir/Subspace Emissary Bros./@comment-12498802-20160210182229

Got some ideas for when the returning bosses fight you.


 * Petey Piranha (Boss 4): Similarly to Brawl, he kidnaps Peach and Zelda at the start of the game, leaving Mario, Link and later Kirby to chase him down. Note that the princess you rescue in this fight is more critical than in Brawl.
 * Rayquaza (Boss 8): About halfway along his trek to rescue DK in Konga Jungle, Diddy bumps into Rayquaza. At this point, Fox comes in out of nowhere, and the fight begins.
 * Porky Minch (Boss 12): Porky Statue is shown chasing Lucas through New Pork City. You must fight Porky Statue four times before Ness turns up and destroys the statue, leaving Porky himself to fight the player.
 * Ridley (Boss 16): Attacks Terra Branford (new fighter, from Final Fantasy VI) and Pac-Man as they approach the factory where the Varia Suit is being held.
 * Ridley (Boss 20): Attacks Zero Suit Samus and Pikachu when they attempt to take the Varia Suit. After defeating Ridley, META Ridley comes out of nowhere, leaving Samus to take the Varia Suit without putting it on, and the two to jump on miniature spaceships to fight Meta Ridley, space shooter style.
 * Galleom (Boss 24): Fights Inkling, Mega Man and Marth on the mountain. After being defeated, Galleom jumps off the mountain to fight Lucario and Ike on the ground.
 * Duon (Boss 28): After Diddy, DK and Fox knock a horde of Mr. Game and Watches (who also serve as Boss 27) off the Corneria, they transform into Duon to fight Mario, Link, Kirby and Peach/Zelda. Before the fight, however, Lucario and Sheik come in out of nowhere, and Fox jumps down from the Corneria to join the fight.