>>47862917The games say that Cosmog (and by extension its evolutions) is an Ultra Beast
The anime says the same thing, and also says that Necrozma is one, giving it the codename of UB Black
The TCG labels DW, DM, and Ultra Necrozma as Ultra Beasts, but not base Necrozma
Generally speaking, what
>>47862930 said. They're considered UBs lore-wise, but mechanics-wise, they're Legendary Pokemon.