With the popularity of Dragon Ball FighterZ, many were hoping that characters from the storied anime and manga franchise would find their way into Super Smash Bros. Ultimate. However, those dreams have been dashed by director Masahiro Sakurai himself.
In a recently-uncovered interview in Japanese, Sakurai stated, “It is impossible for manga characters to join (Super Smash Bros.). While we can accept characters from other companies, we cannot, under any circumstances, take in anything and everything under the sky.”
So while Goku and his allies and enemies may be the hottest thing in fighting games at the moment, their roots in manga prohibit them from existence in the Smash universe.