I completely agree that some of these would make better alt costumes for already confirmed characters. But that's been blown out of the picture when Lucina was revealed. Sakurai explained that there's just enough differences to allow Lucina her own spot. I'm sure this also applies for Dr. Mario and Dark Pit.

I should also wait for official confirmation from Sakurai on the characters, but everything so far from these leaks seem pretty believable that it's hard to call them 100% fake at this point.