Kaido willingly entered hybrid form even when Luffy is out of commission. He knows he can't take them down in Dragon form. Zoro has done the most in making Kaido feel threatened enough to go hybrid. Call it a feat of Enma if you want but Zoro's actions in the past two chapters played a pivotal role in forcing him into hybrid.
Like I said
They did nothing.
Nobody forced Kaido to switch forms with their attack(s)
Zoro has done nothing. This chapter again, Enma hyped
It's not because of zoro or enma... at least the provider didn't mention the reason why Kaido went hybrid
We know he went to human form coz he got bored and wanted to end it...not because retainers proved they were ~ Oden in Power as he himself noted
So here... the question is
Did Kaido acknowledge them to be ~ Oden?
Or to be legit threat?
Let's wait for Thursday
For now...Kaido didn't feel threatened by anyone's attack to a point he switched forms by force after being hit.
Only Oden did that... g3 did that to a drunk kaido.