I was going in kinda dreading this battle, if I recall correctly I ended up having to rely on revive-spamming Mimikyu to win it in my last run, but I'm not using Mimikyu this run and have been avoiding giving anyone Z-crystals.
Things went surprisingly well this time. My team was around level 61. I lead with Decidueye, who dodged the first Photon Geyser, thank you Refresh, and gets off a crit Spirit Shackle that takes it down to about 1/3 HP. (Max affection + scope lens makes my Decidueye a crit machine). Decidueye tanks a second Photon Geyser and survives with HP in the red, a second Spirit Shackle knocks Necrozma into the red. Decidueye goes down on the next turn, my +Speed Ribombee comes out, attempts to Dazzling Gleam, gets one-shot by Power Gem without getting a move in. Pangoro comes out next, tanks a Dragon Pulse and survives with HP in the red, and deals a finishing blow with Crunch.