for both of them, i'm pretty sure it'd depend on whether or not they get to keep their abilities or not.

if they don't get to keep abilities, carter dies early. she's probably not the first death, and she might be smart enough to keep herself out of trouble for a while, but not too long.

if they do keep abilities, the same thing happens, only she comes back and probably dies multiple times over. possibly indefinitely unless the capitol has its hands on that bee-suppressing smoke stuff.

or if someone's got the means, time, and drive to actually kill her and have her stay dead.

either way, she's totally not willing to kill people, she's not going to win.

meanwhile, nyx is a ghost and doesn't understand how getting picked was even possible?

assuming no abilities/au'd into being a plain human, she's sneaky enough to mostly stay out of trouble, and enough of a fighter to come out on top most of the time if she can't.

most of the problems she'd run into i think are mostly because 1) she's fragile, and a fight with someone too much bigger than her would rely a lot on surroundings and being smart

and 2) having too much fun/gloating/wanting to mess with people

nyx would totally get caught up in messing with her opponents and forget to, y'know, actually kill them before they can retaliate.

with abilities, she is still a ghost and is sort of ???? about whether or not death is possible for her. she would be confused and then mostly be incorporeal and hide.

or poison people! it's a tossup.