What if, these five character replaced Luffy/Zoro/Kidd/Law/Killer on the rooftop?
Boa Hancock/Lucci/Sanji/Marco/Sabo.
How would they have performed against Big Mom and Kaido?
These guys are some heavy hitters as well.
Boa can't do much unless her powers work on Homies, but her finger guns might hurt, and Haki Snake would be really funny. However, at her level, being Intermediate with all Haki makes her a genuinely useful combatant. However, unless she Hakiblooms, she doesn't pose as much of a threat as Luffy.
Lucci has the stats to keep up, he's definitely stronger than Post-Udon Luffy, even without his Rokushiki or Haki. Rokugan busts the insides of the target, so it might stun them for a bit, and the regular Rokushiki let him minimize damage taken and maximize damage dealt, as well as amp his mobility. His recovery lets him keep up, and adding in his use of some level of Kenbun, as well as Intermediate Buso, makes him a real threat if unchecked. He's definitely more dangerous than Zoro was.
Sanji is fast and has high mobility. That'd be his thing. He also can put some serious force into those kicks. Diable Jambe and Ifrit Jambe amp his speed and power, burning and possibly even temporarily blinding the opponent with heat and light. His Cybernetics let him resist attacks with his iron body, and speed him up, even making him stronger. They also let him regenerate. He's got Intermediate Kenbun and Buso as well, making him yet another real threat. He's definitely more dangerous than Kid was when he wasn't using his Awakening.
Marco is an interesting case. While inferior he was a threat to the admirals whenever they got locked up in a 1v1. Sure, he takes a lot of hits that punch through him, but that just happens when you're known for having regen, ask any Dragon Ball fan. He's a regenerative beast, and can heal others for support. He can negate flames, has Undying Thistle to amp defense, and uses two types of Haki. Another serious threat. He can perform better than Law when he wasn't using his Awakening.
Finally, Sabo. We know he beats out Killer. I estimate his overall skill with Haki is at least a bit better than Lucci's, and he's an intangible firebender that can only be hit with special techniques and Haki. He also has his own secret move that hits pressure points or something. He's gonna be a serious threat in the beginning when he starts twisting Prometheus and Boro breath so that they hurt each other with their own attacks.
Overall, I doubt they'd win without Awakening any new powers, but if Kaidou went "I'm gonna be the first guy who ever kills all the Straw Hats," he'd be boned.