Hey everyone; just found this forum, so thought i'd join up
From what i gathered from 3D's is that -
The whole point of it was do the mark of mastery and retrieve the power to save Terra, Ven and Aqua.
For the 7 Lights:
During the long conversation at the end between Mickey and Master Xehanort; Mickey mentions that the seven lights are: Sora, Riku, Mickey, his three friends (Terra, Aqua and Ven) then doesn't say the seventh but we know that its Kairi. However due to Terra being still Terranort at this point by the looks of things; I think that Lea will replace him until Terra is saved (probably via waking Terra's heart up by pushing out Xehanorts heart to take back control of his body)
So it will probably be Sora, Kairi, Riku, Ven, Aqua, Terra/Lea and Mickey
For the 13 Darknesses:
Now the Darknesses gets a bit tricky but I think it might be one of two possibilities
During the game; Axel and a few others wake up back to normal and later on he mentions that not all the Organisation is there so that means they awoke somewhere else. So taking away Vexen/Even, Xaldin/Dilan, Lexaeus/Aeleus, Zexion/Ienzo and Roxas we are left with 7 Organisation members; we know Xigbar/Braig and Saix/Isa are part of it already along with Xemnas, so if the other 4 are still in there then that would make it
Master Xehanort, Young Xehanort, Xemnas, Ansem, Xigbar/Braig, Saix/Isa, Larxene, Marluxia, Luxord, Demyx; which makes 10, then looking at it Terranort is probably there and I think Ansem/Riku will be there as seen in Pranksters Paradise. So thats 12 out of 13, the 13th was going to be Sora but that messed up so at the moment we don't know who the 13th would be.
However the problem with that is that we never knew Larxene, Marluxia, Luxord or Demyx's reals names or where they came from so for all we know they could have become proper humans again. But in saying that; i doubt out of the original Organisation XIII that only Xemnas, Xigbar and Saix are the only ones, so possibly a couple of the 4 may be there and the rest are filled with different Xehanorts that we haven't seen.