>>43217034At the end of movie 20, when we see brief scenes of all the regions, the Unova one has the entire Gothitelle line front and center alongside a goth girl, all the other pokemon are out of focus and their faces can't be seen. It's like they chose this line to "represent" Unova for the 20th anniversary movie.
Before that, the Pikachu short that came with the Genesect movie, "Pikachu & Friends", marked the debut of Sylveon. It mostly stars the gang's pokemon and all the Eevee line, but during the third act the entire Gothitelle line shows up alongside Weavile and Gible to give a spectacle, and they appear througout the credits going on adventures with everyone else. Keep in mind, this was the debut of Sylveon and the fairy type, and the last Pikachu short of gen 5, and out of all the Unova pokemon besides the main characters they chose all three members of this line.
Recently a Gothitelle had a cameo in Twilight Wings
>>43222336 wich may be a minor thing but of all the pokemon available they decided Gothitelle was fitting for a children hospital.
And there are other appearences and nods to the line, like in a Kalos episode where Clemont builds a robot Gothitelle maid.
Even if fetishists aren't crazy for this pokemon, the fact that it keeps getting these nods over other unova pokemon has to be for a reason.