So essentially not what you see in that video, though it makes me laugh for how true the discussion can become.
Here is what I'd like to see happen:
in addition to all the characters from Brawl and the confirmed newcomers:
Bring back Mewtwo and include the ability for Mewtwo to morph into his new form(s) for final smash(s)
Give Wolf a new moveset
new characters:
Paper Mario
Wart(Doki Doki Panic/Super Mario 2)
King K. Rool
Chibi Robo
Toon Zelda/Tetra
Midna and Wolf Link
Vaati (from Zelda series) or Ghirahim (I'd lean more toward Vaati since he's been in more games)
Masks Link - Take Young Link from Majora's Mask, and have him alternate between his three forms: Deku, Goron, and Zora Link. (Similar to how the Pokemon Trainer switches between the three pokemon). The final smash would have to be putting on the Fierce Diety mask and being a badass that way.
Plusle/Minun Team
Isaac (Golden Sun)
Mike (Star Tropics)
Captain Rainbow
Geno (Mario RPG)
Bomberman
Pac-Man (a Namco character is incredibly likely given they are working on the game, and he appeared alongside Mario in the Mario Kart arcade games)
And now for my never gonna happen character but would be amazing if it did:
Banjo Kazooie
Putting Banjo Kazooie aside, I know that this would bring the total of 3rd party characters to 6, which I know is a large jump from the 2 in the last game. But I do see no reason that Snake and Sonic wont return. With Mega Man confirmed, and the fact that Namco is working on the game, it does seem perfectly reasonable that there will be at least 4 3rd party characters as it is. Bomberman is admittedly a stretch, but I'd really love to see him in the game. But Nintendo has gotten the rights to Geno before in Mario and Luigi Superstar Saga (where he appeared briefly in a mini game if I recall), so I don't think its completely out of the question to include him.