Luigi's Final Smash is Much different than Mario's. Thank God Sakurai did that. With Falco, Wolf, and Toon Link having to copy moves (Sheik doesn't count) I thought they wouldv'e made Luigi's a green Mario Finale. We get something better!
Luigi starts to dance while a giant sphere of negative colo takes up alot of the stage. Anyone inside the sphere will move in slow motion and take rapid poison damage. Eventually, Luigi stops dancing and can move at a normal pace to attack slow moving opponents. Note: If you're going against Luigi and your caught in the sphere, you can still get out, and won't take anymore poison damage unless you go back in.
Yay for Luigi being made different. VERY different.