My theory is there will be 26 members of the Straw Hats to represent each letter of the alphabet. This also synchronizes with the Pirate King Gol D. Roger's crew number.
Seeing how both Usopp and Nami have been drawn with hints of Conquerors Haki. I think there will be some "technical" Conquerors users as well. If Perona joins, her fruit ability acts in a similar way of suppressing the opponent's will.
Since Luffy's crew is the ultimate version of all the great pirate crews, I'd say he'd at least have the collective of all the CoC users of these crews. This would include the Rocks crew and other unconfirmed users. If I were to list them, I'd say Roger, Rayleigh, Scopper, Whitebeard, Ace, Big Mom, Katakuri. Kaidou, Yamato, Shanks, Mihawk, Xebec and Shiki would represent the total at 13 which is half the projected total crew members at 26.
Therefore, I'd say half the crew will be "CoC" users.