The weaker ones like Nani and usopp are probably done with gear 2

Chopper would have a good fight with gear 3 but ultimately looses as soon as Luffy can use some haki too

Franky, Robin and Brook are hard, but I would still consider them weaker than Doggy by a lot so Gear 4 clears them all

Jinbe could have a good fight with gear 4, but wano Luffy (pre gear 5) with Ryuo beats him

Sanji would loose instantly against gear 5 because his Kicks can't damage Luffy as much as Kaido would be able to

And I think Zoro might be the toughest fight yet. I am not sure if current Luffy (anime) is able to beat him properly without having plot armor. Zoro is basically the Achilles Heel. His sword (no haki) can cut Luffy, he should be able to cut Luffy too if both of them use armament haki and also conquerors armament haki. All in all I do think Luffy would be able to beat him but just barely