Hiya. You must be Clemont the Gym Leader Ashy Boy told me about. I’m Gary Oak, a Pokémon Junior Researcher in Kanto.  Me and Ash used to be rivals in becoming the Number One Pokémon Master. Now, we're great friends because... I needed a best friend and share my passion for Pokémon with someone.

Heh, see that, Aidan? Cyndaquil dodged Squirtle's attack because he felt your trust in him. That clearly shows that you've been training your Pokémon right. 

Alright, I have a hypothesis. No Pokémon that can naturally create such a wide area of rainfall exist in Kalos. Not like we’re in Hoenn. The rain also seems to not affect Pokémon immune to Water type attacks so I’m guessing the condition is spread through the skin most likely. I don’t wanna say this, but I suspect this thing is man made to an extent.