Okay so this is something completely different.
Nintendo just made things a whole lot more complicated for Super Smash Bros. Ultimate players with "spirits." Think of them like augmentations: there's primary and support spirits, which can be used to power-up characters. You'll win them by way of "spirit battles," which are basically fights featuring the aura of characters that didn't make the cut like Mega Man 9's Astro Man and Chibi Robo. Multiplayer spirit battles are confirmed.
One example given is fighting a "Guts Man spirit" by facing off against a giant Mega Man in the Guts Man stage. Nintendo is going all out with these cameos: I'm talking Otacon from Metal Gear Solid kind of wacky. It's taken even further with a Pokemon-like feeding and upgrading system, as well as the power to level-up and do "missions" when the game is off. Yeah, this is going to be a time sink.
Get a look at some of the appearances in the gallery below.