The event was held at the Yokohama Stadium. Attendees were only allowed to enter the stadium if they had tickets. The event was scheduled to last from 6:00pm and 9:00pm JST. Each attendee was given a card with a QR code on it, which was to be scanned at a PokéStop or Gym to permit use. There were three Gyms at the stadium, and neither one could be taken over by any Team.
Once the attendees were inside they were instructed to watch a short video about the arrival of the latest Raid Boss; Mewtwo. The legendary Pokémon from the Kanto region appeared in all three Gyms and was only available for 15 minutes. Each Trainer had a chance to capture Mewtwo. Once Mewtwo was defeated, each Trainer received 50+ Premier Balls to try and capture it. The capture rate at this event was the same as it was at Pokémon GO Fest; with nearly a 100% capture rate. Anyone who failed to capture Mewtwo was given one anyways as a credit to their collection.