(Let's try one more time...)
I decide to continue the crossover ask list
The Chain are sent to the Universe of...
(I'm most familiar with the anime-era, so I'll just use that, sorry to be basic)
The Bad News: the Chain has no idea what chakra is.
The Good News: the Chain has no idea what chakra is.
Whatever it is, they don't have it, because they're not from this universe. Everybody born here has a least a little bit, but the Links? Not a single drop.
On one hand, they're a dead zone with anything that would require chakra. On the other hand, they're a dead zone with anything that would require chakra. They can't use any of the techniques, but they also can't be affected by any of the techniques. There's nothing for it to affect, there's just not a chakra network in their bodies. And this makes them simultaneously terrifying and infuriating to all the shinobi in the area.
Can't sense them, can't kill them by any chakra-based means, can't even touch them really. The only thing that works is the old-school basics, such as seeing them with your eyes or stabbing them with your knife. Which, really, would be fine and manageable if it weren't for the fact that all eighteen of these impossible strangers are alarmingly good at old-school combat. And when a shinobi is too busy being flabbergasted that their jutsu didn't work... well.
It's a good thing these impossible strangers end up being friendly?