345ash-greninja
Auto-Memories Doll
*This also goes for @Dragalge as well*Screencap that, so you will have a proof when the league comes. Also, since pikachu it's fighting it in the OP, it's possible... except OPs are known for be very, very misleading.
Except Zeraora is appearing in this episode and the summary also makes it seem extremely likely that it has a trainer too, so the opening being misleading here is extremely unlikely if you look at it.