Yup, I really think we're going into the USUM-marketing phase. Rockruff evolving connects to the Lycanroc-shot from the trailer, then we got a special animation for Mimikyu and that's what we're getting here, then we're getting a new trainer with a Brionne (which may serve as a rival to both Ash and Lana) and we get a Dhelmise reveal, which is just sweet, but it could be a great Totem or Gym pokémon if they switch it all up.
When it was first revealed, I did say the Lycanroc was there to symbolically suggest something was going to happen to Lycanroc, aka third form, but maybe the specific aspect in the game was Midday Lycanroc as a totem Pokemon because it was subtlety hinting at a 3rd form, or perhaps even a Z-move.
Same with Togedemaru also being a Totem Pokemon or other shared possibilities.
Mimikyu is the weird one since its already a Totem Pokemon in Sun and Moon, but it could in a different place since the ultra sun and ultra moon showed it outside (maybe the Megamart isn't closed in U. Sun and U. Moon).
So yeah either Mimikyu gets a new form, or a z move.
And since this episode happens after August 10, I think its possible that maybe Mimikyu could find a strange Z-crystal and it won't be revealed to Jessie, until later, where its actually exclusive to Mimikyu.
Or maybe this episode could just be about Jessie and Mimikyu, and Mimikyu won't go off doing its own thing anymore, and actually allow Jessie to command it at all times and not just against Pikachu.