In the trailer, through a combination of shaky cam footage and lo-fi creepiness, we see a researcher documenting a snowy landscape within the Hisui region (where Arceus is set), only to encounter what he believes to be a wild Pokémon.
When the two ultimately meet, it ends in death. Or at least injury — the trailer cuts out before we can tell, but things don’t look good.
“The tip of its tail is red and swaying ... It’s adorable ... The white fur on top of its head and around its neck is so fluffy ... Its eyes are round and yellow ... What’s that?! ... Gwaahh!”
Maybe the researcher encountered a mythical Pokémon, leading to his untimely death. Based on the geographical location, one can assume there will be some ice-type Pokémon that should be approached with caution and not, say, right up close with a video camera.
Overall, the whole trailer functions like a found-footage horror movie. I guess we’ll just have to parse the video for potential clues until Arceus releases early next January.