That's fake. The dialogue has been edited.This screenshot from Pokémon Masters would confirm this.
Likely a dub error. It wasn't told to use that move in Japanese. Probably a mistranslation, since Thunder Wave and Zap Cannon sound kinda similar in Japanese.Watching the dub of SM131, Sophocles tells Vikavolt to use Thunder Wave which the captions confirm
Not sure if this is a dub error or new move
According to this tweet:Leon and Iris are cousins.
This screenshot from Pokémon Masters would confirm this.
On the Pokémon summary screen for that location it says "on the tower summit", so it doesn't appear to be a proper, independent location.I know this may not be your field of specialty, but could you let the admins at Bulbapedia know that in Sword and Shield, the location where Eternatus and Zacian or Zamazenta is caught isn't part of the Energy Plant, but another location labeled as "Tower Summit"?