Both will play existing characters from the cartoons and comics who are coming to the big screen for the first time.
Goodman will play Hound, a Transformer who generally takes the form of a military jeep when he transforms. The character appeared in the movie tie-in PSP game Transformers, which is nominally in the same continuity as the movie and features Autobots who have the same basic look as ones you might see onscreen. He was voiced in the game by Daniel Ross. He was depicted in the game as nearly inseparable from Trailbreaker, and a toy has already been shown off at ToyFare, giving fans a sense for what he might look like onscreen (above).
Watanabe will play Drift, a Cybertronian Samurai warrior. If the Transformers Wiki is any guide, it was not already known that Drift -- also a Generation One character -- would appear in the film and no toy has yet been released.
In-story, he's a former Decepticon (then called Deadlock) who defected. He wields his two short swords and Spark-powered Katana and trained under Wing; the katana belonged to Wing prior to his death.
Drift transforms in a red and white Japanese sports "Drifter" car, and bears a striking resemblance to Blurr from Transformers Generations, which used the same mold with different coloring, a new head and different accessories.
Transformers: Age of Extinction stars Mark Wahlberg, Stanley Tucci, Li Bingbing, Kelsey Grammer, Sophia Myles, T. J. Miller, Nicola Peltz, Jack Reynor and Titus Wellive.
The Michael Bay-helmed sequel (his last? He's vascillated on that...) opens in theaters on June 27, 2014.