The Dragon/Earth god and the winged individual on the left are the same entity.
Think of the Dragon as the full Zoan transformation, and the winged individual as the hybrid form.
Both have two horns and wings.
The winged individual holding the sun is probably Imu using the mother flame, the mother flame was probably destroyed or rendered inoperative after the war hence why hes trying to make a new one because the war isnt over as Nika keeps coming back to free the world from the earth gods tyrany. Now the question is if Imu is the original earth god or a vessel like Luffy is to Nika, that is open for interpretation. I think Imu was born in the secon world and inheritted the earth god's powers.
Imu gives people immortality, regen and just powers them up, that is literally something a devil will be able to do. Sabo said that he didnt imagine that the top of the world was actually hell itself, this is after seeing the Gorosei and Imu transform.
Basically the eternal enemy of Nika is the earth god who had humanity enslaved, the serpent is an ally of the earth god.
I think Blackbeard will either ally with Luffy to fight Imu or pull a zetsu and steal his powers but imo it would be bad writting and isnt really foreshadowed in the prophecy at all.
This is basically a story of earth god vs Nika.