Did you play Melee? Luigi's moveset could only be compared to Mario's in appearance, and his style of play is completely different.
Heh, I like how everyone's lamenting the loss of Ness while you are still only assuming. First of all, the "no clones" thing (about which I never actually saw evidence of Sakurai himself saying) would be years old, thus subject to have changed, even if true. Second, we don't know how Sakurai defines a clone (comparing Mario and Dr. Mario is quite different from comparing Mario and Luigi, for example). He seemed to focus quite a deal on the differences between Ness and Lucas in his most recent update. Really, the only move that seems to function exactly like Ness' is his up-B (and that includes different standard moves).
I'm not saying Ness is going to return. In fact, I think there is a reasonable chance he's gone. I am tired of all these posts saying "OHG OD WAHT ISHE GONA DO SINCE NESSS IS DEF OUT NOW!!" when Ness also has a decent chance of being back.