It was announced by Niantic that if players complete all the Global Challenges this weekend to tie with the GO Fest, it will unlock an exclusive day for Zapdos on July 21, 2018. During the three hours on this day, all Gymnasiums will have Zapdos Raid Battles. This Zapdos will have the Thunder Shock Fast Move and will have the chance to be brilliant. The Global Challenge this weekend are:
GO Fest – Complete 100,000 search tasks
Europe – Complete 5,000,000 search tasks
Americas – Complete 5,000,000 search tasks
Asia Pacific – Complete 5,000,000 Search Tasks
Source: Serebii