>>52106151I play the game and have seen the spreadsheet.
Besides psuedo Dragon type Close Combat and not having Weather ability (and yes, a burn immunity is nice and all, you know if Scald wasn't basically Dexitted. That would have actually made it really good too), it's pretty much Tyranitar but as an Ice/Dragon type.
Of course in Gen 9 it'll be top tier, even in a sea of powercreep, but mostly due to the literal main gimmick being Tera. You know, the one thing letting Baxcalibur remove its Ice type weaknesses?
Come Gen 10 when Tera more than likely won't exist, its weaknesses are going to be more apparent. It's going to be extremely hard to set up with this thing because it has 3-4 major weaknesses that you can't patch up with a better typing, and having really mid stats outside of its massive Atk stat and HP. 115/92/86 bulk would be good, but not something with bunch of weaknesses, especially when its best Dragon move doubles damage of your opponent's moves. Its speed is also very slow and can easily can be revenge killed after a Dragon Dance because of said frailty (if it gets off a Dragon Dance in the first place). It's faster than Dragonite and Kommo-o, but those 2 have far better practical bulk than Baxcalibur.
Its type combo is also pretty exploitable too. Ice/Dragon is pretty easy to wall with common defensive Pokemon. With Baxcalibur, you either forgo one of your STABs for covering the likes of Tapu Fini and Corviknight (just to name a few and ones that could easily exist in the future), or you choose to be walled by one and not the other. At least Kyurem-B could take on many of its wouldbe checks with Fusion Bolt, Mold Breaker Earthpower, and Fling (yes it uses Fling), while Kyurem-Grey can get pasts its checks by 130 SpA Freeze Dry and Pressure Stalling. Baxcalibur doesn't get that luxury.