Worstgen
Shiroyru
With the reveal in the magazine of Teach’s two sisters, it’s pretty obvious that they had their souls merged with Teach’s somehow. Probably the work of Xebec trying to find a way to gain multiple DF powers. This is why Luffy and Zoro referred to Teach as “they”. Both of them sensed Teach’s multiple souls. Marco thought that Teach’s body is weird because he can sense more than one person in there.
Shiroyru
It’s all but confirmed at this point that Teach is getting 3 DFs at this point, and the last one will obviously be a Zoan to complete the pattern. Logically it should be the strongest Zoan since he called the Yami the strongest Logia and the Gura is the strongest Paramecia (when it comes to fighting). So his Zoan DF will be a Mythical Zoan.
Shiroyru
Doubt it will be Marco’s because he would have just made sure to catch him at the Payback War. Not gonna be Sengoku’s because that would make no sense. Devon’s is off the table for obvious reasons. It can’t just be some random schmuck’s DF because Yonko Teach could easily capture them. It’s gotta be Kaido’s DF because he would be unable to get it right now, and the Dragon Zoan being the best Zoan is kinda obvious