I read that Chinchou/Lanturn have the hidden ability Water Absorb. I’m playing Ruby (NOT Omega Ruby) on my GBA, and my Chinchou just took WATER damage. Do Chinchou/Lanturn not have Water Absorb hidden ability in Ruby/Saphire?
Hidden Abilities didn't exist at all until generation 5.
Lanturn didn't have its Water Absorb ability in Ruby because no Pokemon had any Hidden Ability in Ruby. Because they didn't exist.