If anything the entire adult trio is on par to fight. Robin cannot be hit by brute stentgh based off what we have seenFranky has Shogun Franky AND Kizaru lasers, I know his Pink fight didn't show anything past fists but I think people are sleeping on Franky a little. He wouldn't be the one to finish Jack and may not even be a crucial help but I don't think he'd be decommissioned before Jack was put down.
How do you answer a hypothetical question? Really? Anyway they'd do it the same way the base has been doing it for months, his hype which is why I said "is his hype too much for you to consider their win possible?" This isn't a show me proof question it's a how do you feel question. Do you feel Jack's hype is equivalent to the levels we've seen from the SH's it's not that complicated. Also it's really more a question to gauge NB's Jack hype.
She caught on of the fastest characters thus far (habaku) and has taken hits from building throwing monsters (oars) so she should be fine. Brook is immortal and can just drink milk and get back up.