There were two areas in Yokohama that were transformed to into both the Kanto and Johto regions from the original game series.
Red Brick Park
The Akarenga area was transformed into the Kanto region. Pokemon from the Red, Green, Blue, and Yellow versions of the game appeared more frequently.
Cup Noodle Museum Park
This park was transformed into the Johto region. Pokemon from the Gold and Silver versions of the game appeared more frequently.
Over 2 million fans celebrated Pikachu Outbreak in Yokohama the week of the event. Trainers captured over 120 Pokémon and 15 million of those Pokémon were Pikachu. Unlike what happened at Pokémon GO Fest, cell signal and data speeds rarely hindered anyone's ability to play the game.