So, there's been a bit of discussion over the final shot of the new male protagonist with something new on his Z-Ring, which he activates by turning a strange irregular Z-Crystal. There's also a few shots of Mimikyu and Lycanroc in dynamic action scenes, with M lunging at the camera and Midday-L leaping in front of the sun. Some people have guessed that these are forme change scenes, or new unique Z-Moves.

I propose this: they're both.

What if this new crystal is the key to unlocking some sort of Z-Power beyond Z-Power? Z-Megas, perhaps? Combining the Z-Move and Mega Evolution mechanics would be a great way to revitalize Mega Evolution after its use in SM fell flat, and the Lycanroc scene HAS to be a Z-Move or similar animation- think about it: it's clearly jumping in front of the midday sun, and that wouldn't make much sense playing at night in a plot cutscene, would it? I'm guessing this is how we get the much-anticipated "unmasked" Mimikyu form, as well as the mysterious third Lycanroc form (presumably, Midnight's animation would show it leaping in front of the full moon). I also suspect that, if true, this will be how we use the armored Solgaleo and Lunala forms, mirroring how the legendaries in Omega Ruby/Alpha Sapphire showed off a boosted form of the Gen 6 gimmick. After all, it's strange that the box legendaries of the generation that introduced unique Z-Moves didn't get any, but Xerneas and Yveltal didn't get Mega Evolutions, either.

This last point is really just speculation, but if I didn't know jack shit about Pokemon and you showed me that last shot from the trailer, I'd have told you that it's going to have something to do with transforming into another form. Why? Because a bracelet that you activate by twisting a symbol on it just SCREAMS "Japanese transforming hero".