Smash Ultimate Direct August 8th 2018 announced at Evo

[Wyrdness]

AngryLittleAlchemist said:

PAOerfulone said:
Mario and Mega Man were sacrificed so we could have Inklings and Ridley. Luigi was sacrificed so we could have Simon and Richter Belmont. And King Dedede was sacrificed so we can have King K. Rool.

And then Goku will be the final reveal trailer and he'll use the Dragon Balls to wish them all back. :P

Are the dragon balls like the infinity stones?

They're different basically the are 7 of them that need to be gathered in order to summon a Dragon who grants a character a wish, all 7 of them are required so they can't be used by themselves and after each summon they turn to stone temporarily (they need one year to regenerate) and fly high up in the air and scatter to different parts of the world needing to tracked down again.