In the teaser that revealed "Super Smash Bros." as coming to the Nintendo Switch, a handful of characters are shown.
Nintendo is direct about four of them: Mario, Link, and two inklings from "Splatoon" (in the foreground).
The rest are shown only as silhouettes in the shadow of a massive, burning "Super Smash Bros." logo. But we're talking about Nintendo characters here — it's pretty easy to pick out the shape of, say, Bowser from a silhouette.
So, starting from the left, here are the shapes we're able to pick out with certainty: Pit (from "Kid Icarus"), Donkey Kong, Kirby, Marth (from "Fire Emblem"), Mario, Link, Samus (from "Metroid"), Bowser, and Pikachu. Additionally, the two inklings from "Splatoon" are likely new characters.
There are also a handful of shapes that aren't sharp enough to say with certainty who they represent. Our best guesses put those shapes as Ness and Lucas (from "Earthbound"), Captain Falcon or Ganon (from "F-Zero" and "The Legend of Zelda," respectively), Little Mac (from "Punch-Out!!"), Princess Zelda, and Jigglypuff.