You still get 2hko'd regardless and these calc's aren't even for specs kyogre meaning you won't be switching in and if kyogre comes in after your ttar is on the field spout will OHKO.
after stone edge hits, water spout will be hitting for significantly less damage. a second stone edge or a crunch+sandstorm kills off kyogre. im not saying that tyranitar should switch into a kyogre.
i am talking about scenarios where both are used as leads or tyranitar gets a free switch into kyogre and in that instance, tyranitar will have the weather advantage.
Using Assault Vest on Ttar means you are practically begging Xerneas to Geomancy in front of you and proceed to 2hko with moonblast (ohko's after some prior damage) or straight up get ohko'd by focus blast while you do neither.
which is why i said that tyranitar would be good for picking off a weakened xerneas lowered to about 50% or lower.
focus blast would only be doing about half, moonblast, even less and tyranitar can KO it with iron head. nobody expects iron head on tyranitar and said xerneas would likely attempt to set up thinking that said tyranitar cannot do much damage.
This is not OU so almost all the time you will see a physical luke being used in Ubers and Close Combat OHKO's regardless of whatever Ttar you choose. Furthermore Aura Sphere 2hko's so once again you cant switch in.
i have seen a lot of specially offensive lucarios, or at least they werent purely physical. i just posted those calcs with lucario as a testament to t-tars bulk and its ability to hit back hard.
i have been in situations where lucario has used aura sphere on tyranitar and it just got OHKO'd in return with superpower.
Standard Ttar also tanks an aura sphere and ohko's back, not to mention due to a fall in power quite a few guys run Focus Blast on MMY which 2hko's meaning a well timed prediction on an obvious Ttar switch means you get 2hko'd before being able to do anything to it.
i have never seen focus blast used on mega mewtwo y. either way, relying on focus blast as the only way to hit t-tar is treading on very shaky ground, unless they run focus blast+aura sphere, which is just ridiculous.
Most importantly Assault Vest means you cannot use support moves meaning no access to stealth rocks (and roar) which means you need another mons slot to be free for rocks which is an all time important move and puts even more strain on teambuilding as you have to get proper checks for the above mentioned checks outside of ttar being a one time switch in only and you also become set up fodder to certain threats.
While Ttar is usable in ubers due to certain niches assault vest is probably the wrong way to go about it (imo atleast)
tyranitars stats seem too solid to me for it to merely be a hazard setter. if this were the case, i could just use smeargle. what tyranitar set do you have in mind for ubers?