I wouldn't be surprised if the Habunake did have a minuscule role in this episode, but I think other wise since there's also a Zangoose on the poster. Some posters made good points about the possibility of it belonging to Musashi or a Team Plasma agent. However, I think the writers might just have Musashi rely on her very new Pururiru for now, even though I wouldn't mind seeing Habunake again since I've grown to like its design due to fanart. Like someone else said, Musashi mentioning she previously owned one would be nice, if not for just the sake of continuity and all that jazz. The chances of it belonging to a TP member seem likely, however I wouldn't count on it completely since the writers probably would give more time in-between TP appearances. I'm just gonna take a wild guess and say that the Zangoose and Habunake on the poster are indication that we'll get an episode centering around the two fighting against each other or together, those two Pokemon supposedly have been feuding for generations against each other.
I would prefer if this was a Tag Battle battling against Zangoose and Habunake, with Iris/Satoshi or Iris/Dento since Iris hasn't really had a real Tag Battle the whole series. If it were Iris/Satoshi, I'd want to see Zuruggu and Kibago, if it were Iris and Dento, I don't really care what Dento uses anymore but I'd want Iris to use her Kibago. Of course I wouldn't be surprised if this episode was just an episode featuring the two battling each other or something, I'm just hoping for an exciting episode. I'm kinda surprised the writers haven't had an Aianto/Kuitaran episode yet since those two, like Habunake and Zangoose, aren't exactly the best of friends and it would have been entertaining. Oh well, hoping the best for this one. Once we get a title that should be a more valid judge of what plot the episode will have.