Stellar Tera? Serperior seems like a very sub-par user of it since the move just boosts a given Type 1 time for 1 move use, which means Serperior's MO of utility to spam Leaf Storm to win gets very little out of it (and it's pure offense without anything like type-flipping to survive a would-be KO). The Contrary inversion of the Stellar Tera Blast boosts sounds good in theory but it's for a weaker hit giving a lesser boost on something that's Pure Normal vs a non-Tera target.Considering that Serperior is very likely to get banned as well due to Stellar Tera, I feel like we're gonna need to have clear proof of that mechanic being completely unhealthy for the meta, otherwise the Council will probably just resort to quickbanning both mons and call it a day. I guess we're gonna have to wait and see how good that Tera actually is.
If Serp ends up unhealthy I'd expect it to be from regular Tera, whether Tera Blast for coverage or even Tera Grass to brute force Leaf Storm harder.