While it is true that being a pseudo-legendary isn't completely out of the question, let us look at Aurumoth again.I very much doubt it. This thing will most likely have egg moves, pretty much. Which rules out legendaries as an option. Besides, pseudo-legendaries are only defined by the 600 BST - the immunity is an inconsequential observation (as in, they are not an official Nintendo class of Pokemon, they just happen to have a recurring BST - I would be more than willing to bet that the immunity is coincidence, and no more than them all being able to surpass 400 Attack (until Garchomp) or all having attacking stats of 130 or higher (until Hydreigon...)).
Ask yourself the following questions:
-Can I see this thing within the same status as all the other BST 600 Dragons?
-Could I imagine two pre-evolutions that would look good and not seem unnecessary?
-Compared to other Bug-types, does Aurumoth portray the sort of creature to have gender and reproduce?
If you were honestly hesitant about answering yes to any of those, it goes to show that clearly Aurumoth is above being just a regular Pokemon. Therefore, it definitely isn't out of the question to call this thing legendary and disallow egg moves at the expense of creating a larger level-up pool. That is where I propose that during the Pokedex Entry submission stage, in addition to including misc. flavor such as height, weight, and gender ratio, each submission must contain the listing of whether Aurumoth is legendary or not. An example submission looking as so:
This of course would mean that we'd do Dex submissions before movepool submissions so as to not conflict with egg moves and flavor, which isn't out of the question given that all steps in the CAP process must take place eventually regardless. We should all have the vote to decide whether this thing is legendary or not.Height: 5'4"
Weight: 70lbs. (BP 80 Low Kick / Grass Knot)
Gender Ratio: Genderless
Hidden Ability: Shield Dust