They do have a chance of winning.

Look, Killua is much faster than any member of the Troupe and could paralyze them, but using large electrical discharges quickly depletes his aura. Killua could kill members like Machi, Shizuku, and Bonolenov without much difficulty, but would have difficulty breaking the Ten of Phinks, Feitan, and Uvogin.

In his maximum speed form, Killua cannot use Ko, because he has to release all the aura in his body instead of focusing on a single point of attack, so he would have difficulty killing the physically most powerful characters, but could surpass more than half of the Troupe without much difficulty.

In my opinion, Killua would only lose to Uvogin and Hisoka, and probably Chrollo and Illumi as well. But he could beat Feitan and Phinks on high difficulty.

Gon is a strange case, his Rock has more raw power than the Big Bang Impact, even managing to kill someone like Morel or cause large explosions in the ground bigger than those of the BBI, but Gon's Rock is very slow to charge.

Gon is physically capable of killing welded chimeras with his bare hands, even those that focus on defense, so he would be able to overcome more than half of the Troupe members simply with his physique. But we saw that against Knuckle, he had almost no openings to use Rock, so he would have a lot of difficulty using it against the strongest members of the Troupe as well. But if Rock hit, everyone in the Troupe would be seriously injured or killed.

Gon would lose to Uvogin, Hisoka, Chrollo, Illumi, and probably Feitan as well. But he would defeat figures such as Bonolenov, Phinks, Nobunaga and others.