It can work in OU. It has the movepool and the friggin speed to annoy the hell out of offense.
Anw: here's a thought
Leave Gen7 out of Reborn entirely
Reborn started in the BW era, where there were a lot of things. Strong, threatening things. But a lot of them were legends and another lot of them were based a lot on perma-weather, so that leaves them now both out of the equation. They are not big factors in balancing.
Gen6 introduced only a couple of evolutionary lines that made a difference in that regard: the three starters, Talon, Aegis, Klefki and the worst pseydo ever. Fairy retyping did some shuffling of pre-existent stuff and that's it. That's where Reborn is right now.
What Gen6 brought and Reborn hasn't even explored yet is the multicoloured galaxy of megastones. And now we're upon a new generation that brings a) new Pokemon lines (3 starters and then a handful will matter, hopefully), and a multitude of new formes for preexistent ones. This can be hella tricky, since it'll force a complete reexploration of the balancing and distribution, which isn't even up to stuff.
Not to mention that it'll have to introduce that Z-move mechanic, propably.
Reborn is complete at around a solid 65% to 70% I think. Even now, stuff is being pushed backwards. With that mindset and the current reality of quality TMs and Megastones being absent so far, and with the massive influx of new stuff in Gen7... I think the best option is to steer clear of that. It's gonna be way too packed that way, and it's gonna be a lot of work putting all that stuff in the game.
Hell, I'm kinda dreading the amount of stuff left to be put in the game with 4 episodes left.
Also I don't know how to interpret the signs: GF gives new formes to oddball choices like Eggy, Sandslash, Marowak, and also fan favourite Ninetales. Should we think that all of Kanto is getting Alola'd? Only some lines? No idea what to think of it... but either way, that's gonna be way too much