Just a reminder that this is the discussion thread--if you want to post here, please make sure that you're contributing something to the discussion!
As for my thoughts: I could see this going any of the three options, given that we have precedence in all cases with Pokemon with a BST of 600. However, I feel like it doesn't fit the exact mold of a pseudo-legendary. All of the pseudo-legendaries seem to focus more designing a "cool monster" (or cute, as Goodra is), and the ability isn't a defining trait of the Pokemon. Meanwhile, this design puts heavy attention on the art motif, and its ability is a defining trait. I agree with Tenshi that these traits make it match something like Meloetta more in how thematic it is. In addition, while this is mainly opinion, I think the design seems like a "unique encounter" rather than an entire species, which also tips it towards legendary/mythical flavor.