Woah ok lots of evolutions. Wasn't to fond of Silvally when I saw it in CoroCoro but the video and artwork do this thing justice. As has been pointed out, RKS System sounds like Arceus, but the design, wow. Also, I think it's confirmed that Gladion gets Silvally, as he seen behind it with the Type: Null breaking mask picture.
The -o line is interesting. It evolves to train itself to defeat some sort of darkness. Mabye it will be involved in the plot of the Ultra Beasts, who knows? But I find this line kinda meh design wise. Not a fan of the scales everywhere because it looks weird.
Riombee looks like a bigger cutifly, that's it.
Ok, look at the video. WE HAVE A RAINBOW MUK. IT'S A RAINBOW AND IT'S A MOVING RAINBOW I LOVE ALOLAN MUK. Design wise, I hate Alolan Grimer, I understand it's meant to be ugly but ugh, I hate it. Alolan Muk gets a free pass because IT'S A RAINBOW.
Ilima graduated from Trainer's School huh? Well, they sound like the first trial captain we'll meet, since other Trainer School graduates have roles early story, such as Roxanne.
Olivia has a Z-Bracelet, meaning Z-Moves. Also big shame to learn that she's a rock type kahuna, meaning other kahunas will have type specialties to.
I'm neutral toward this annoucement tbh. I love Silvally and Alolan Muk, but Riombee, Bounsweet Evos and type specialist kahunas ruin it for me.