Something tells me Tapu Koko is going to die.

Of course, he'll probably be revived at the end by the box legendary or something.

Story-wise, it makes sense to me. Everything is going as it always had in Alola. Somehow, these dangerous and powerful creatures make their way into the Pokemon universe (maybe this was due to Aether Foundation's involvement) and threaten everyone.

Tapu Koko appears to save Hala when one of these ultra beasts arrive. Tapu Koko underestimates it, is utterly destroyed by the ultra beast.

Suddenly everyone realizes the danger that these beasts pose to everyone, and eventually the box legendary helps the protagonist drag these beasts back to their dimension and save Alola.

It's an amazing and fresh storyline. I think the idea of these extra-dimensional creatures invading the Pokemon universe and disrupting everything and forcing everyone to band together to fight them back is really exciting. I'm just scared for poor Tapu Koko.

And who knows, maybe we'll get a chance to catch these ultra beasts. Maybe one of the Aether members creates a way to weaken them or turn them into Pokemon.