Good luck with that...with +550 moves, it's gonna take a looooong time.
EDIT: Then again, someone could potentially do Metronome-based battles like in previous generations and record the result through VS.Recorder... --- "Many of you feel bad for this lamp...That is because you're crazy. It has no feelings! And the new one is much better." (IKEA's Lamp commercial)
"Drawing power from the Eternal Flower, the user fires a powerful beam of light. This also damages the user quite a lot." Although no other details about the move were leaked here, this has been speculated to be the Fairy-type signature move of Diancie. People have also made a connection between this and AZ's Floette, who was given eternal life by the machine that was turned into the ultimate weapon. The description matches that of other 1/3 recoil moves. If this is a special move, it would be the first ever special recoil move, not counting Volt Tackle in Gen III. The page has been taken down already, but it's archived here, thanks to GameFAQs user JC152.
They prevented Metronome from selecting Freeze Shock, Ice Burn, Secret Sword, Techno Blast, and Relic Song in 5th gen so they likely did the same thing here. Hasn't stopped Light of Ruin from showing up in the Hotel Richissime room service meal names, though.