Mysteries of the Pokemon World
I saw an interview with Satoshi Tajiri where he talked about how he started developing games. He said he was obsessed with Xenvious, & that there were lots of rumors about the game which he had to try out. It's kinda appropriate then that a game he developed spawned a similar storm of rumors. I'm not in favor of rumors per se, but I still miss the mystery you'd get back in the day, & I'm glad, in a way, that similar rumors existed for later games like X&Y.
Kids would trade stories about what they found, or heard someone else found, in the games. Separating real from fake, however, was nearly impossible. You just had to try to find things for yourself, to see what was real.
Others remember rumors of new, rare Pokemon species, like Pikablu or Buru. None of these rumors were unfounded. The TV show had introduced 2nd generation Pokemon early, & Topps used Pikablu & Buru instead of Merril & Snubbull on their promo cards for the 1st movie. (Don't know where they got those names; I assume they got them from 4Kids or Nintendo, & that the names were changed before the film was dubbed. I never collected Topps' Pokemon cards, but I would like to have those for the weird name variants, if what I read is true.) Mew was mentioned in game; anyone who completed the Pokedex would've realized there was at least one character missing. Maybe more.
Of course, even if they weren't unfounded, most of the rumors were false. Marril & Snubbel weren't in the first games. There was (probably) nothing under that truck. But other rumors were true. There really was a strange Pokemon, named Missingno or Pokemon M, off the coast of Cinnabar Island who could give you a (seemingly) infinite ammount of rare items. (One of my couisins showed me that trick; I later read about it on a cheat code site & memorized the steps to find him. This was the same site which had that go-to-Johto code, & that stone-to-evolve-Mewtwo code.) There was a way to really catch Mew, without going to Nintendo's special events. There was a way to access strange, etheral cities, a way to walk through walls, an invisible computer in a hotel, etc. Thing is, these weren't supposed to be part of the games; they were bugs, but we didn't know that. I assumed Missingno was inserted by the creators intentionally, as a way to help young players, or as just something else mysterious to discover & exploit. I even tried to find him in Crystal, surfing up & down Cianwood City's coast looking for him. I tried other, similar locations as well.
Eventually, I learned the truth; that these strange Pokemon were just glitches. I still had fun with them tho.