When I first saw this, after Brock entered the "cabin" after leaving Gliscor I was wondering when they were going to mention Gliscor. And when the narrator started talking I was actually worried it would end without anyone mentioning Gliscor.
But then that ending scene happened and it was funny.
Gliscor and Staravia sure made this episode funny.
As to why Pachirisu got sick, I think it was because Ash "accidentally" doused Pachirisu in cold water.