A guide on how to complete Request 16: Strange Happenings at Midnight in Pokémon Legends: ARCEUS (PLA).
To begin this quest talk to Sanqua, who’s found near the row of houses in Jubilife Village. She’ll ask you to check out her house, because she’s been hearing strange noises and finding berries around.
You can only investigate her house at night, so if it’s still daytime you’ll need to hang around for a bit until it gets dark. Upon entering the house, you’ll be able to first investigate the table to the right of the entrance. Then, head up and investigate the pot and the clothing. You’ll hear some more rustling and you’ll have to check the table by the door again, and then you’ll hear something near the clothing. A Pichu will pop out.
Sanqua will enter at the sound of the noises, and discover that the Pichu is a friend. Upon helping her discover the source of her problems, she’ll reward you with x7 Nanab Berry.