We know that Black is stronger than Goku. This has been a fact since they fought for the first time in the future, when Goku surprisingly said that he was a terrifyingly strong villain. And when he transforms into Super Saiyan Rose (name given after the color his hair acquires when transforming), he gains an extraordinary power. It is not like Goku has fought badly or without using all his power, but that Black (who in truth is Zamasu using the Saiyan’s body) has let his body receive damage, so that he can grow stronger, raising his power level with each battle.


Yet the big question remains…If Black has Goku’s body from the present time, why is the villain stronger than our hero? Why is there so much difference in power level?


First of all, when Zamasu wished, with the Super Dragon Balls to exchange bodies with Goku, he empowered himself. Probably the wish itself produced some sort of effect in Zamasu (already as Black), that can be understood as an empowering of Goku’s body, skills, and limits. In other words, the wish gave as a result an enhanced version of Goku’s body, maybe because of the mix of the Saiyan’s body with the ki of a God such as Zamasu (since he ascended to Supreme Kai).

All this gave birth to Black, a hybrid being with the skills of both the Saiyan and an evil Supreme Kai.

In fact, Vegeta himself confirms this when he accuses Zamasu of corrupting the Saiyan cells. Yet the prince of the Saiyans was wrong when he said that only Goku was able to control that body, since we’ve seen Zamasu controlling it quite well so far. That may be because that body isn’t Goku’s body any longer, but something else, a hybrid. This is a big difference with Captain Ginyu’s change technique, since he only tried to manipulate a foreign body such as Goku, without much success, and he was not accustomed to it.


Let’s see

Black's case is different, and this is probably the reason why his Super Saiyan transformation is Rose instead of Yellow like Goku or Vegeta. His body is not a pure strain Saiyan, it is an anomaly, a hybrid, an alteration made by Super Shenron. The fusion between the evil spirit of Zamasu, and the overwhelming ki of Goku, created a formidable warrior that seems to have enhanced the skills of both Zamasu and Goku. This is why his Kamehameha is so destructive, and Zamasu’s blade techniques so precise.

Now Goku’s big challenge is to deal with all of this -- while trying to prevent the villain from becoming stronger.