Sure The way I see it, you are only exceeding the minimum requirements. Some users have already produced black variations of their own sets.

Can more than one set be featured in the same piece?

Sounds great, hope I can find time for this.

Good idea, I have long wanted to draw a similar

Must find time! :C

I like chess. 

Chess pieces based on existing characters and etc are fine

The count is off likely due to one of us mods deleting a spam comment (I am guessing).

Can the pieces be based on existing things? As in if I based my pieces on, say, several Pokemon (like Charmander as a pawn) or if I depicted an existing character as a chess piece (for instance Wreck-it Ralph as a rook), would that be fine? I had a quick idea of having chess pieces that are modelled after existing characters but I just wanna make sure if such is allowed.

Also where's the third comment? The number beside the speech bubble says "4" (was 3 before I posted) but one comment appears to be missing 

Creative scenes are allowed. Just make sure that each individual piece is at least featured once without it being obscured by another piece.

Each piece a size limit... does that mean that one can't feature the pieces in a creative scene, but they have to be displayed one by one?