I've got a few theories in my head after looking through the teambuilder. Haven't tried any of them so they'll probably be meh at best.
- Kommo-o with a dragonite-esque set - will probably be UU but might be seen in OU occasionally
- Physical Pivot Silvally with perfect coverage in Fighting Memory and Shadow Claw - again, probably UU due to its average speed
- scarfed Xurkitree, mowing down teams with t-bolt coming off 173 base sp.atk - I'd say BL, I don't think it'll be very popular in OU since Tapu Koko outclasses it as an electric type in general, but it seems hella strong for UU (EDIT: now that I think about it, Xurk might actually be used alongside Tapu Koko for terrain-boosted t-bolts, actually sounds kind of terrifying)
- scarfed Kartana, for exactly the same reasons as Xurkitree, but physical - also probably BL, but could breach into OU popularity
- Alolan golem is basically electric mega Glalie but not weak to rocks, slower, and doesn't take up a mega slot - definitely will have a niche in RU