GO Hub has brought some interesting information to the Western world. The Indian App Store (for iOS) is now featuring an ad for the new Pokémon GO update, saying the following.
"Special Pikachu with Hat and first legendary Pokémon"
Trainers from Singapore have now reported that their App Store is now displaying the ad within the last hour. If this leak turns out to be accurate and the advertisement spreads to more countries, Legendary Pokémon appearing at Pokémon GO Fest Chicago, the Pokémon GO Chester Heritage Event, and Pikachu Outbreak is all but guaranteed. Niantic has promised new details on these events (which have been given for the Chester event) in the next few days. In the meantime, check out the screenshot below that GO Hub shared in their article (ad in center-right).