It's a waste of any character, aside from Emperors, if they get paired against Zoro.
They should be paired with someone who can give them a extreme diff fight.
Zoro would mid diff all Calamities, in worst case high diff vs King.
Since Luffy is helpess against Big Mom's sword, Zoro will probably protect him from her.
However, Franky seems to have taken care of Napoleon for now with his stunt.
So Luffy could try to deflect her attacks now once he got the hang of Haki flow.