I like this article a lot. Parallel City + Captivating Pokepuff seems like a very nasty combo indeed, especially with the absence of Super Scoop Up and AZ. Ninja Boy seems like it could fix a situation like that, but that doesn't mean your opponent can't Lysandre around that and grab a free two prizes from Shaymin-EX.
Parallel City could also be used to nerf Water Box, Serperior, Flareon-EX, and any upcoming Electric-type decks (Raichu and Zebstrika, most likely). While the -20 won't hurt too much, it can mess up some math and give your side an advantage for a while. Zebstrika can still one-shot Clear Humming Altaria, in spite of the damage drop from the stadium, but even with weakness, Zebstrika still can't OHKO Mega Rayquaza with Parallel City. It'll do 90 (since you're losing 20 from PC), which becomes 180 due to weakness. It would help if you had something more along the lines of Muscle Band, but that's rotating. If any anti-Ray deck wants to one-shot it with Zebstrika, they're gonna have to use Giovanni's Scheme to OHKO it. It has two uses, so your deck doesn't really lose consistency by dropping a Shauna or maybe an N.
Parallel City would also be pretty devastating to Rayquaza. Limiting your opponent to three on a bench cuts Ray down to 90 damage, and then, assuming they get Sky Field, they have to find more Basics to fill their bench with, drastically cutting their resources. Bunnelby might be a good option for M Ray decks, but it's extremely weak. Ideally, I wouldn't want to put too many EXs on my bench to satisfy M Ray's attack, because Lysandre is still a thing.