Maybe because Ash battling this one character LEADS to Emolga and Team Rocket, somehow.
Not everything has to directly revolve around something.
Even if that were true, would anyone honestly expect such a battle to last more than a few seconds? And if so, would anyone really get a kick out of seeing Exploud for such a small amount of time? Like I said before, I had never seen anyone compliment the species before so I'm surprised that Exploud is suddenly being heralded as the second coming of Christ.
But of course I don't truly believe Exploud will have an important role here, as I don't have any faith in the writers to be able to juggle more than one event in this to be honest.