Jinx fits the Project skin line pretty well, imo. I was requesting this skin for ages already.
Especially because she is insane, it just goes extremely well with the theme of a malfunctioning cyborg. Which probably is also the reason why they gave to her in that exact line. The theme was "we can't control the monsters we created". I think Jinx got abandoned as a failing Project, because of said malfunctioning.
Same most likely for Pyke, who is also kinda crazy in his base skin. He seems corrupted.
Warwick is literally a man-made monster, so he gets a spot here.
With that thematic they were going for, I would question Akali and Irelia more than the other 3. But I can see why they probably still went with them, like I said in another thread.
I guess it is because of the whole war with Noxus shtick that Ionia has going on.
Irelia became a leader of a resistance, she throws away all the old traditions about balance since she understands that they have to defend themselves and fights Noxus head on.
Akali left the Kinkou order, since she started to realise basically the same. You can't fight Noxus with "balance", the old traditions don't work here. So she became an assassin and kills as many Noxians as possible without putting herself in chains that the order calls "balance".
So the war made these champions abandon their old concepts of peace and balance, making them "monsters" on the battlefield to protect Ionia, but forgetting themselves along the way.
About Pool Party: we are most likely not getting these skins this year. We got Arcade instead, now Project and they will also give us Star Guardian in the near future. Pool Party might return next year, tho.