Update: The new trailer has been added.
Original story: Hard to believe he wasn't already confirmed, but yes, Yoshi has been confirmed for the new Super Smash Bros. on Wii U and 3DS during today's Smash Bros-centric Nintendo Direct. But that was merely the appetizer for the next major character reveals, both hailing from the Pokemon world: Charizard and Greninja!
Greninja comes from Pokemon X/Y and uses his Water and Dark-type ninja attacks to deliver Sheik-style hurt onto opponents. Meanwhile, Charizard separates himself from Brawl's Pokemon Trainer to not only show off his fire-based attacks, but to also reveal his Mega Evolution!
As for Yoshi, he returns with many of his attacks intact, including his egg tosses and flutter jumps, only this time, he'll be standing upright.
Masahiro Sakurai also revealed that characters would not undergo transformations in this iteration of Smash Bros, meaning that Zero Suit Samus and Sheik will both appear as standalone characters. That makes a total of five more additions to the Smash Bros roster.