First off, why does Sans have time stop again? I'm a bit new to this change to him.
Also, does Sans use Time Stop during combat.
Anyway, AFAIK, Sans is able to hold the player in place by, during his turn, not finishing it. That's something that's a part of Undertale's combat system.
Presumably, Sans is able to do that "take my turn & not finish it" in other settings because of Verse Equalization, which lets him still do his stuff as though in his 'verse.
So could he still pull that "not finish my turn" stunt when he's taken out of the equalized/Undertale battle system?
Not to mention, the Undertale system was still able to be cheated by someone outside of the combat system, IIRC, when Chara did a 2nd slash after Sans, asleep, dodged the player's 1st slash.
Also, OP says (At the time I'm typing this.):
Gumball has all equipment. Speed equalized. Fight takes place in the Elmore Mall. They start 20 meters apart. Gumball has an hour of prep (if it even helps). Gumball is in character though is determined to kill Sans.
SBA for anything else.
Can Gumball turn on the console during that hour of preptime?
Can he menu to an attack or such?