Is there something about swagger that we don't know?

Question

So, I was in a Battle Royal in the battle spot.
The Pokemon on the playing field were my Klefki, an Incineroar, and two Tapu Kokos. Electric Terrain was in effect.
(Klefki's ability is Prankster.)
Because my Klefki's ability allowed it to use status moves with priority, it moved first.
Klefki used Swagger!
It doesn't affect the opposing Incineroar...
Why?
Electric Terrain prevents sleeping, not confusion.
Incineroar's ability is Blaze (because Intimidate was not released yet).
Does Swagger not work on Dark types? Or is there an item to prevent it?

Answer 1

No, it is known why this would occur. It is a consequence of a new balancing mechanic that was added in Sun and Moon, where all moves that are affected by Prankster do not affect Dark-type Pokemon. Since Swagger gained priority from Prankster and was used on a part Dark-type Pokemon, the move didn't work due to this mechanic.

Whilst this does impede on Prankster's usefulness, it's still one of the best abilities in the game. You'll just have to be a bit more cautious in how you use it, since it's open to counter-play now (i.e. opponents can switch to a Dark-type Pokemon if they anticipate a Prankster move).