Unfortunately, Goku’s first SSJ3 transformation against Baby Vegeta doesn’t last more than two minutes. He quickly loses power, as his child body is unable to retain the form. As Old Kai later ...

Goku's battle with Baby saw the debut of the iconic Super ... it's a brief clash that serves to show how completely ...

It’s the same issue Goku had with the transformation. Super Saiyan 3 Vegeta has a lot of power, but it’s not a form that he can sustain for long as it drains more of his stamina than the other ...

Just like how Super Saiyan 3 was seen as a seemingly exclusive form for Goku for many years before Vegeta uses it in Dragon Ball Daima, Vegeta using its power here is a way to make up for lost time.