On April Fool’s Day, someone leaked almost every little bit of Pokemon Let’s Go Pikachu and Eevee and not a single person believed it.
They got the fact that they were Yellow remakes (they are spiritually) for Switch, and that there’d be two versions (Pikachu and Eevee). They said that following Pokemon would return and that the game would have Pokemon GO integration including catching Pokemon which works as it does in GO.
They also leaked the Pokeball Plus accessory which would work in both game and in Pokemon GO. Lastly, they also said the game would release this year and would be announced soon.
Obviously, it’d be possible that they could have guessed a few of these things, but it’s insane to think that literally every bit of information was correct.