Shulk (SSB4)/Side special/Default
Shulk's side special in SSB4 is Back Slash. Shulk jumps up a small distance, then unleashes a wide-ranged downward slash with the Monado; if used in the air, he falls at a slightly diagonal trajectory with the Monado held out. As the name implies, the move deals more damage and knockback if it hits an opponent facing away from Shulk. It is a risky attack overall; a frontal hit does moderate damage with minimal knockback and hitstun, making it very punishable along with its ending lag, but a successful hit to the back is a very rewarding attack, dealing high damage with the Buster Art, and serving as one of his most powerful KO moves with Smash. It is worth noting that Shulk's back throw can combo into a Back Slash at certain percents with Buster.
However, Back Slash is extremely dangerous to use off-stage, and despite its slight lateral movement, it is not recommended as a recovery move; when Shulk uses this move, he cannot cancel it at any point, cannot change his trajectory, and cannot grab a ledge at all, usually causing him to self-destruct off-stage.