Pelkas in one word, unreliable. Pelkas can often disappear during a game for many minutes. His A-game you could say is better than Mystakidis but not by much. Mystakidis on the other hand is consistent. I have not seen him drift in and out of games the way Pelkas does. He also has a tendency to score goals during tough games or when the team really needs a goal, whereas Pelkas tends to play at his best when the pressure isn't on.
All this sounds like I don't rate Pelkas. I do, but he has a long way to go. He's still a boy. Mistakidis is far more developed in my eyes even if he isn't as technically gifted.
As for Fetfa, I can't take him seriously for the NT. He's 25 years of age and he's spent more minutes in his career on the bench than on the pitch. Don't be seduced by the flicks and tricks. There's a reason why he's been riding the bench most of his career.