On the "Raw" sheet, flag 18 appears to implement the Metronome exclusion list, but without regard for which moves have been snapped. Moves that haven't been snapped, but are nonetheless incapable of being learned by anything in the dex, can probably still be called by Metronome as long as they're tagged for it in this column.
Thanks! Apparently we lost Moongeist Beam/Sunsteel Strike/Nature's Madness (also snapped) from the Metronome pool, and a number of ordinary new moves are unusable for whatever reason, if this list is what it looks to be. Odd move by gamefreak if true. Like, Branch Poke? At least they didn't just make every new Gen 8 move unusable but it's really weird.
Also, the PS dex is missing the ORAS additions of Dragon Ascent, Hyperspace Fury, Origin Pulse, and Precipice Blades in its Metronome description.
Interestingly, Accelerock and V-Create are still flagged as true.
Mat Block, Fairy Lock, and event moves like Celebrate/Hold Back/etc are there too. So there are a few moves that are still 'usable' but unlearnable, not too many though.
I like how they were able to get rid of everything that learned Hyper Fang, probably the least exclusive move there.
-----
I'll wait for the release date and mechanic testing to see how it all works in practice, but this "CanUseMove" stuff is looking to remove some of Metronome's power attacks. My dream scenario is Metronome being able to call the removed moves with Flag 18 since they have all the attack data, maybe not the animations. Probably won't happen though.
Also Clangorous Soul is a dance move. Lol