No tera ban! What would be gen 9 without tera? Thats like saying removing Z moves from gen 7, dynamax from gen 8, megas from 6-7, like it feels like doing a disservice to the mons themselves that benefit from it. If they get banned, go use them with Tera in Ubers if you care that much. If they all get unbanned then they turn OU in HO hell.
Now for Bloodmoon:
Take into consideration that unless you have a Corv with heavy HP or sp. def investment, a Tera-Ghost Weezing (G or base), or a max HP max Sp Def Unaware Clefable, then the Big Bear WILL be claiming KO’s. There are 2 big factors that can completely crush whether not you can counter it, and all are very viable in there own right because of the inherent strengths of the mon.
1. Item - The big 3 are leftys for setup, Silk Scarf for breaking, and Assault Vest for survivability. These add a layer of volatility!
2. Great Moves - Blood Moon, EP, CM, Moonlight, Vacuum Wave. 5 moves, but change one and you have a completely different set.
Lack of counters to the variance albeit minimal, is noticeable due to the overwhelming base power of the mon. It can brute force through checks easily with slight variance in set