I can't recall the site my friend was on, some sort of pokemon news site, some stuff in Japanese though English.
It's been a while since they cut them out, heh but most people dont know they dont exist.
If you want to post in it for speculation or just general discussion feel free, seeing as the revival rule doesn't apply to the episode discussion section, but I'm pretty sure that a date hasn't been confirmed, unless I've missed something. Do you have a source? :3