Thanks for all the tips!
I caught it. I had to sacrifice Raichu to do it, so Butterfree gota safe swap in but I caught it. Suprisingly it didn't set up aqua ring until I had already slept it 2x... but by then butterfree had 2 quiver dances up. So it's attacks were doing nothing, and it was getting outsped. (Butterfree has keen eyes and sleep powder, I figured this was the safest option since all other sleep inducing moves have really low accuracies.)
And yes, it was just a chore and I was frustrated. I had soft reset tapu bulu like 15x before that, because I kept killing it with Ice attacks trying to lower it's hp enough to false swipe it without it taking 50 turns XD. On the brightside lele only took 2 tries, and koko took one. If I ever restart this game, forget necrozma, fini is def getting the masterball. Lol
Now to grind out levels painstakingly so I can get the pokedex done and start breeding for shinies with good IVs XD