Dark-type for Alolan Muk makes perfect sense. It looks like an oil spill, and the crystallized trash in its body is a pretty clear reference to pollution as a whole, which ties in with the environmental aspect of Sun/Moon. Also, Dark-type is "Evil"-type in Japanese, so.
Also, Bounsweet is going on my team immediately and I require a plushie of it ASAP. Tsareena is fierce af, though I do low-key wish for it to be Grass/Fairy. I'm not too bothered personally though because it seems likely the Popplio line will pick up Fairy, which is what I'm starting with. Other than that, I might entertain the thought of using Ribombee for a while in-game, but it won't end up on my final team most likely. The other Pokemon reveals today were pretty meh for me, tbh.
Also, is Ilima even confirmed to be a girl? Jw because the article specifies that, but I don't see that evidenced anywhere on the site/trailers. Pretty sure that they're a boy, imo.