Q:
Where can I watch the preview for the upcoming Japanese episode?
A. PLEASE DON’T CLICK THE FOLLOWING LINK IF YOU WATCH THE DUB VERSION OF THE ANIME AND DON’T WANT TO KNOW ABOUT RECENT EVENTS IN THE JAPANESE VERSION IN ADVANCE.
TV Tokyo, the main channel broadcasting Pokémon in Japan, has begun uploading the previews onto their own YouTube account
here. The previews usually show up a few minutes after they have aired on TV, which means almost every Thursday at about 7:30 PM JST. Once the according episode has aired (in other words, after one week approximately), the preview video will become private, so you won’t be able to watch older previews there.