How so? Let's take Arceus-Ghost as an example. Zekrom deals 49.6 - 58.9% with Bolt Strike (assuming Scarf and Adamant Nature). Then, Arceus-Ghost simply burns it with Will-O-Wisp and Recover while Bolt Strike fails to KO.
Also, what exactly does Scarf Zekrom revenge? Not GeoXern. Not Mega Mence. Not Groudon-P. Not ExtremeKiller. This means it can't even do it's job properly, which is to revenge kill sweepers.
Sorry if it sounds unappreciative, just that on paper, at least, it seems to not be very good at doing what you claim it does.
It has enough defense to revenge kill Arceus normal if healthy also your Arceus Ghost stat is irrelevant because that means Arceus Ghost cannot switch in on it since it gets 2hko'ed like I said. And no what I'm saying is not only good on paper. I don't say shit only good on paper when I talk I talk facts and practice sir. I would like you to reread what i wrote, Some very solid teams have only Groudon as a Zekrom check. So it's used to overload Groudon and doing good support overall. It's also good to bring it vs some specific opponents in official tournaments. Enough to be in B rank.