Shulk was revealed in the August 29th Pic of The Day, a redeeming quality to an otherwise boring news week. I won't be going into full analysis of him but he plays a little differently than other characters, using his Monado Sword to control what stats he has at a time, and Sakurai goes in-depth in his Pic of The Day:
"Pic of the day. From Xenoblade Chronicles, Shulk joins the battle!! He's not the type of character that would usually appear in the Smash Bros. series, but we worked really hard to make it happen. We're very happy with how he turned out. This stage is Gaur Plain."
Images by Smash Bros. Miiverse
"Shulk's sword, the Monado, slashes enemies with a beam when activated, so it can strike from long range. What really makes this weapon unique is that when the Monado Arts are activated, it can change Shulk's features and abilities! Emerge victorious in battle by changing your abilities strategically!!"
Sakurai gave each Monado Art, describing the pros and cons of each. These arts are very valuable to Shulk and his moveset, and are unique to him.
[List of Monado Arts]
翔 (Jump): higher jumps, lower defense.
疾 (Speed): faster movement, weaker attacks.
盾(Shield): higher defense, slower movement.
斬(Buster): stronger attacks, weaker launch ability.