Luffy needs to save everyone in FI from Noah so he decides to use his elephant gun.
Instead of using his strongest attack, King Kong gun, or at least G4 Kong Gun attack what's your much stronger than any of his G3 attacks.
Zoro had the save the king and everybody else on top of the plateau so the first technique he used was a name attack.
Then the rest of the attacks on the golem are none name attacks. He cuts the golem up with those attacks. Which proves he didn't even need to use the name attack to initially cut the golem.
He then use a weaker name attack against Pica real body than he did against the Golem.
You see Zoro didn't even need to use his billion fold
Zoro ultimate move is asura.