>>33854346Lusamine dressed up Lillie as a Nihilego because she was going crazy and Mohn's notes on Nihilego (who likely had his judgment affected by the toxins) were the last things he left behind.
Pheromosa and Lusamine's similarities strike me as leftovers from a more elaborate plot involving all of the UBs. Consider that Pheromosa also uses chemicals to affect people's judgments and it's not entirely crazy to imagine a different version of the story where Lusamine is obsessed with Pheromosa instead. I could go a little more in-depth with this and Pheromosa inexplicably getting Ice coverage, Lusamine's frozen Pokemon, and Ice being the only type without a specialist in Alola, but that's heading too far in theoryfagging for my tastes.
Xurkitree and Guzma honestly just feels like a coincidence. Xurkitree has a light + plantlike + electricity theme, so its central organ/"head" looks like light radiating in all directions, as well as possibly a star atop a Christmas TREE and maybe even "mad scientist"/static hair. Guzma is going for a skull motif, so he dyed his hair white to make his hair + shades look like a skull.
