Absolutely has acausality both from scaling to Vector Prime but also the Alternity have causality manipulation and they’re pretty useless against him, the transtech saying he exists beyond linear time, his tfcc bio stating he has no beginning or end
In the same comic we learn about Vector being able to manipulate causality he’s said to be so insignificant Unicron doesn’t notice him
Reality warping is weird, because he’s stated to be able to do it several times but we rarely, if ever, actually see it. In Omega point his species are said to be “omnipotent” which, obviously don’t take that at face value, but essentially they could do anything relative to their series.
This is a retelling of the Marvel origin basically. I wouldn't get hung up on it referring to a single universe too much, as this origin has been retconned several times to mean the birth of the multiverse. Even the DK Ultimate guide actually says Unicron and Primus existed across countless realities during their initial fight, so this retcon has been around since the early 2000s.
Stated to distort reality in this TFCC Story Withered Hope
Also he can actually use his powers to create things but chooses not to. Dark Lio Convoy in a recent manga used it to rejuvenate a planet and stop earth from exploding, and iirc in Superlink/Energon they use his energy to fill another universe with life or something. Also above thing about him being able to create time.
Regarding Law Manipulation or Power Nullification, the former depends on how literally you take his statement of being "the collapse of the natural order" and Forest Lee stating the rules of the multiverse (physics I believe) were shaped by the 13. I don't know if I recall an example of outright Power Nullification, Unicron's main thing is being just inexplicably immune to basically any method of killing him permanently (even the Star Saber used several times failed to kill him, and while weakened multiversal variants of him still exist Post-Shroud) or manipulating reality around him. Inexplicable as in the actual canon explanation is "he could never be totally destroyed" with little reason given beyond that. Ramjet's also said to be able to warp reality and he gets his power from Unicron. Unfortunately I don't think we really see it used though.
Existence Erasure I would think yes, based on him destroying his own race of abstract conceptual entities and being able to destroy every other plane of existence.