As mentioned before, Team GO Rocket was trying to take over the Festival of Lights. With Giovanni now having control of a Shadow Lugia. The 15th part of the Misunderstood Mischief requires to defeat 3 Team GO Rocket Leaders to get a Super Rocket Radar. This one can be used to fight against Giovanni, and you should. Because completing the Special Research before the end of the month will unlock the an additional Special Research.
I waited a bit before fighting Giovanni until there was Windy weather ingame so that the Shadow Lugia would be weather boosted. Unfortunately it seems that didn't really help me out at all, because as you can see here I only got a 1-star Shadow Lugia.
One of my friends didn't wait for Windy weather, and got around an 80% IV Shadow Lugia. So yeah I guess it doesn't really matter if I waited for the weather boost or not. I don't even really feel like leveling this one up xD
I'm hoping that with the next GO Fest we will be able to get Shadow Entei, Raikou, Suicune, Ho-Oh and Lugia from Special Research like we got Shadow Articuno, Zapdos, Moltres and Mewtwo during the first global GO Fest.
From one of the Team GO Rocket Grunts I fought I got a 0% IV Shadow! This Shadow Cacnea shown right here.
It's now my 2nd or 3rd 0% IV Shadow that I have.
Did you catch your Shadow Lugia already? Tell me and show it in the comments to have a chance at winning a Hive SBI at post payout.