Hella

As Demily stated, both games are arcsys games, but Dragon Ball Fighter Z was their first game in that particular engine. The movement system was set up such that only one character (our titular Goku) actually had the code for movement, and every other character essentially had a line of code that said "see how Goku does it, and do that."

This has a few benefits. It decreased the amount of code needed per character, made it easier to tweak the movement across the board, and was really funny.

This same movement and mechanical system and engine would follow into the next Guilty Gear game. But why change the reference point if it still works just fine? So all the characters in that new engine ALSO had the code that said "go see how Goku does it, and do that."

So in the depths of Guilty Gear Strive's files, there is a lone Goku. In the wrong place, in the wrong timeline, holding everything together by being the only character that actually has the code for the core game mechanics.