The Super Saiyan that has passed the level of that third …
To explain the Super Saiyan Blue (now SSB) that will appear in the game, we will have to start from the basic form of the Super Saiyan God (SSG), which makes its first appearance in the movie Dragon Ball Z: The Battle of the Gods and the first narrative arc of Dragon Ball Super (both manga and anime), who takes care of adapting the film.
We start from a quick review: as the story of the movie and the anime / manga set between the last chapters of the Z series, the form of the Super Saiyan stronger currently known is that of the third level (which at the time was only reached by Goku and Gotenks): any comparison of strength, therefore, must exclude the forms that appear in GT, such as the famous Super Saiyan 4.
The SSG form is an ancient legend of the Saiyan race, which tells of the existence of this powerful form, reached long ago by a Saiyan warrior who intended to stop the evil faction of his relatives, but failed to intent on account of the limit of time that has this form.
During the events of the film, we see Goku asking Shenron what the method is to achieve this transformation. And there is to be said that this is a completely unique method, which has nothing to do with all the other forms. To reach the level of SSG, six Saiyan moods are needed to infuse their strength into one of the six participants in the ritual. It is through this ritual that Goku reaches for the first time the form of SSG in order to fight Beerus, the divinity of destruction.
The SSG, visually, is very different from other forms of Super Saiyan: the main difference is the hair, which in this form is colored red, and the skin, which takes on a slightly darker color. As we have mentioned, this form has a time limit: it consumes very quickly the Saiyan energies, so Goku is not able to stay long in this form.
To compensate for its relatively short lifespan, he thinks of his power: Goku SSG is able to compete with Beerus, who has defeated his Super Saiyan form without any effort. In Dragon Ball Super manga , Vegeta also reaches this form, and can use it at will just like Goku, while in the soul instead you see nothing of all this.
Beyond the divinity
So far we have talked about the SSG, the form that is based on the SSB that we will see in Dragon Ball Fighterz . It appears for the first time during the events of Dragon Ball Z: Resurrection of ‘F’, and during the animated adaptation that the saga received in Dragon Ball Super (in the manga this saga was skipped and briefly summed up in a table).
The achievement of SSB is simpler to explain than SSG: here, in fact, there is no complex ritual involved. Super Saiyan Blue is nothing more than Super Saiyan’s force applied to Super Saiyan God: for this reason its full name is Super Saiyan God Super Saiyan.
In a nutshell, if Goku turns into Super Saiyan starting from its normal forum, it becomes a simple Super Saiyan. But if it first transforms into Super Saiyan God and then, by SSG, becomes Super Saiyan, it becomes a Super Saiyan Blue, a form that takes its name from the particular color of hair. According to Toriyama, the choice of blue color would be due to the fact that Goku, after reaching the SSG limit, has now reached an even more powerful but at the same time quiet and balanced, characteristics of which blue color is a symbol.