Please keep in mind that this is just a theory and not a fact. On DB Super Episode 57, we learned that Zamasu and Black are two separate individuals. This raises the question, who is Goku Black? I personally believe that Goku Black is from either Universe 7 or possibly Universe 10. He can be from any other universe. Many ask, why is he evil and why does he have Goku’s body. I believe that Zamasu used the Super Dragon Balls to revive Goku’s body from any universe. At this point, anything is possible. If Goku didn’t die in another universe, it can be possible that Zamasu used the Super Dragon Balls to turn Gowasu into an evil being, and then he could have used Goku’s body to fuse it with Gowasu. Many of you will ask why would Goku Black not look like Gowasu. I read something in a YouTube comment from a user that said something like “when it comes to two characters fusing, the character will always look like the strongest one.” Do you guys believe this is true or not? In Dragon Ball Z, Vegito and Gogeta look like a combination of both Goku and Vegeta. However, Akira Toriyama is known to make inconsistencies through out the sagas, and it could be possible that the rules for fusion apply differently in DB Super.
Why does Goku Black have pink hair and not blue hair? The super saiyan blue transformation is meant for saiyans that are purehearted. Since Goku Black is evil, that could be the reason as to why he has pink hair. Correct me if I’m wrong with the way I express myself, but the pink color or pink rose in Japan is supposed to be associated with death. Because Goku Black is evil, it makes sense to me for him to have pink hair.