Black Maria went from the nicest and most lighthearted of the Flying 6, to easily the darkest and most sadistic.
And Robin showing why what Sanji did meant so much to her specifically. And he was aware of what he was doing, not just submitting to Maria's demands.
Yamato's fruit choice is appropriate for what it means to the theme of this battle. The Legend of Momotaro, to be precise, because it includes a dog companion with some more significant role. Sorry, Inu, I know you're one of the Scabbards, but you aren't exactly "Key figure" material.
The wolf god Yamato's fruit is based on also is depicted visiting Yamato Takeru, who's story Yamato is inspired by. Specifically the part of Yamato disowning Kaido as their father, is reminiscent of Yamato Takeru being disowned by their father, who is an Emperor (Yonko).
As far as I can remember, Yamato Takeru was said to have also helped establish Kumamoto Prefecture, where Oda lived.