It's implied in B2/W2 that Hilbert and Hilda went to another region after they defeated the Champion in Unova. If you go to Nuvema Town and go to their house, their mother initially thinks Nate/Rosa is her child, before realising her mistake, and she says she wants to go on her own journey to find her children.
In the anime, Lillie developed her fear of touching Pokémon after a Nihilego almost swallowed her up when she was younger, but no-one else knew about it because she tried to suppress the trauma. In the manga, one character says to Lillie that she looks like a doll, to which she just says, "Thanks..." Another scene then shows Lusamine putting the Nihilego-inspired clothes on Lillie, almost against her will.
This is going by the games specifically since the anime and Lillie's look is its own thing compared to the games entirely. (Lusamine isn't a control freak in the anime, just a VERY neglectful mother. The clothes don't mean anything other than fitting the mood and the Z Powered form is just Lillie willing to be more brave!)
Lillie never even got to pick her own clothes out until you advance in the games. Her ditching it for her Z Powered form has the same meaning in both SM and USUM as her deciding on making her own life choices. She still has that old look in USUM and people scream that is a plot hole due to the changes in Lusamine, but it isn't really one if you consider it a coincidence.
The Manga, while they showed us Lusamine insulting Lillie's Z powered form and forcing her in that dress. I still stand with what I said because people specifically called Lillie a doll and no one saying anything about the look after people saw Nihilego.
I'm also ticked off at the Manga for taking everything away from Lillie that made her great in both games (Even USUM where it took her away from the focus and climax) and even the anime. (Which did something else.)
To put it here... she only had one outburst after the PTSD scene, the second Cosmog came out of nowhere and rendered her taking Nebby as absolutely pointless, Lillie never got to blow the flute that evolved Nebby or really do anything to help out.
The half a year thing contributed to nothing but Faba taking over Aether.
Nebby should have found the dex holders sooner and the Aether Siblings are far away from the Poni Island conflict. (Nebby is with the Dex Holders... exactly where Lusamine is heading towards.)
If the big Lusamine fight is just between her and the Dex Holders, I will officially use that the next time someone who praises the manga bashes USUM or the anime for making changes to the vanilla SM story. (I got bigger gripes against the SM Manga and it is a shame since I heard and seen Adventures do better.)
