Let me just say that this episode was needed for the sole purpose of showing off what else Pokémon Connoisseur's can do. Therefore it's not filler.
To be more precise- It's not a filler in between two canon events; Finding out Opelucid Gym is closed in the start, going to Virbank City in the end.
I mean we were going to find more about them eventually. That's for anyone who thought this episode wasn't needed as Cilan got no development.
People who think it is unbelievable for Cameron to be strong because he is this idiot kid clearly have not been viewing anime properly.
Anime has proven that characters don't always have to be geniuses to win in a battle, for some people brawns is what works for them.
In fact, Cameron is basically just another Ash. Ash too is dumb, the main character, the guy you're always rooting for.... DO YOU SEE?