Requiem Aeternam
Dance like an eggplant!
That's why I run Z-Happy Hour on mine. It gives Lycanroc that extra speed, power, and bulk it desperately wants. I haven't tried the Battle Tree in Ultra Sun yet, but in Sun I didn't really see any difference between regular battles and the super battles, only super battles give more BP and you can streak beyond 20 battles. In terms of actual difficulty I don't think they're different at all.
Unfortunately mine is bred so Happy Hour is out of the question. The Battle Tree is pretty much the same except in the non-Super streaks your Pokémon are no longer scaled to 50 and you can use banned Pokemon like Necrozma and Mewtwo.