So, basically as the title states.  As of the E3 2018 trailers, I decided to compile a list of all confirmed Guardians of Light and Seekers of Darkness, any blanks you can speculate on below, and I will post my thoughts for who else could be added in the list as well in ().  To note, I will not be including Donald and Goofy, because I believe this will recreate the Keyblade War, therefore all participants will be Keyblade Wielders.  I do think they will play a part, but will not be part of the Lights.  Also, I will not be adding Terra to the list of Darknesses because I have a theory I will be posting soon.

 

First, the Guardians of Light

 

1) Sora

2) Riku

3) Mickey

4) Lea

5) Kairi

6) ???? (Roxas?)

7) ???? (Possibly Xion or Terra?  Repliku?)

 

Now for the Seekers of Darkness

 

1) Master Xehanort

2) Young Xehanort

3) Ansem SoD

4) Xemnas

5) Xigbar/Braig

6) Saix/Isa

7) Marluxia

8) Larxene

9) Luxord

10) Vanitas

11) Aquanort

12) ???? (Possibly Ven?  Since Aqua is the only one who can reach him. Possibly Xion?)

13) ???? (Demyx?  Since he's the only Organization member we haven't seen yet.)

Edited July 22, 20187 yr by Azure Flame

After the last trailer I'm thinking Riku Replica might end up as one of the lights

 

I'm sticking with my theory that Xion will be one of the darknesses, specifically the 'missing darkness' YX mentioned in the Toy Story trailer

Ooh, didn't think of that!

I think it's worth noting that being a Xehanort doesn't necessarily mean they're one of the 13 darknesses. It's entirely possible they're just a gambit by Xehanort to move things into place for something he wants to happen. 

Well, when MX was about to make Sora one of the Darknesses, he said he would put his heart in him 'like thre rest' meaning that they all have a part of Xehanort's heart inside them.