With the All Stars I feel like they will probably fight other characters. Like I can see Marco fighting King, the Minks and and samurai will probably fight Jack for revenge on what he did to their village, and with Queen maybe a Luffy and someone will fight him since there has been some build up there, but I don't think people like Zoro will fight any of them. He will probably fight one of the Flying Six until he teams up to help fight Kaidou. Of course there are still the Big Mom pirates that I have no idea what Oda plans to do with. It seems like Perospero will be the first one to arrive there and I really don't know what to expect from that. Plus Big Mom will probably get written around some way with Nami and Sanji figuring something out? I can't imagine anyone actually fighting Big Mom and beating her.
Anyway, so it seems that Yamato is actually a fighter. I was thinking he might be like Momo and be kind of a disappointment, but it seems he is strong. Given his appearance with the Oden style clothes and cuffs I guess he is some big fan of Oden? I really don't know what to make of Yamato's character. He feels like such a random addition to the story and I can't think of a character like this introduced so late into an arc where they are now super important to the plot of it.
So Ulti is a pachycephalosaurus zoan logia. Part of me was kind of hoping she would be the T-Rex, but I guess being a "bone head" fits with her character, haha. I enjoy her dynamic with Page One and I wonder if they really are siblings. Seems she is strong enough for Luffy to maybe go Gear 4? I feel like that little mention was to try and give her and the rest of the Flying Six some credibility. I still wonder if the black lightning means she has CoC or just normal CoA haki. It feels like most of the time when we see black lightning it corresponds to someone who has CoC. I wish Oda would clarify that. I think Oda showing Zoro having a hard time with the Gifters was meant to do the same thing as Luffy saying he needed gear 4 against Ulti, but I still really have a tough time buying any of them being that strong when they have gotten beaten up so easily until now.