They're going to be UU at worst.
They're most likely going to be designed as Solgaleo/Lunala but better and I doubt GF will repeat the same mistake they made with Kyurem Black.
>>33530388
>+100 BST
>will retain Lunala's/Solgaleo's typing
>will probably get access to some of Lunala's/Solgaleo's moveset, including Moongeist Beam/Sunsteel Strike
>will also probably get a new attack for each respective forme
>new ability that'll be a mix of Prism Armor + Shadow Shield/Full Metal Body
To AG and beyond!