At this point, with the way God Valley was appropriately skipped multiple times, Im convinced Blackbeard is literally housing Rocks' soul or possible living embodiment (i.e. a devil fruit like Nika became).
We know Devil Fruits are hypothesized by VP to born out of strong desire for something, and it would not surprise me if Rocks himself, after death, became that for Blackbeard. Im aware that its a theory from VP, and that it doesnt entirely explain how the process works (that people wanted Nika to live on so his fruit became a thing for example), but its the best we have to understanding how DFs are even created in the first place.
What Im saying is, Rocks is possibly to Blackbeard what Nika is to Luffy, a manifestation of world domination vs Nika's freedom. And with that, awakening Blackbeard Zoan would basically lead to him transforming into Rocks himself.
Now Im not sure of the clone angle, as to why Weevil (failed) and Stussy (success) exist from this crew, but I guess that also leaves a few other options for Rocks:
- He was cloned by VP, which Im personally doubting since Weevil was cloned as a failure 35 years ago, 3 years after Rocks "died"
- Imu did something with Rocks at God Valley. This one seems to be gaining traction since Domi Reversi became a thing, we'll see.
- Blackbeard's first devil fruit was that of his father's reincarnated soul after he died on GV, a mythical zoan similar to Luffy's Nika. What I explained above.
All in all though, Im willing to bet that Rocks is not fully "dead", and that somehow he lives on through the above options.