UPDATE Completed Pokemon Go Fest 2021 Global Challenges and Ultra Unlock Progress

Trainers, the Go Fest 2021 event has started and new Global Challenges are now live. Working together and completing the Global Challenges players can unlock the special Ultra Unlock event.
Ultra Unlock is something that many are less familiar with, and to be fair, it is a quite new feature too. The PoGo Fest 2021 ticket holders are the only ones that will interact with this feature though.
This feature will give ticket holders a set of Global Challenge Arena, that have to be completed in order to unlock the next step. When a set number of Challenges are completed, Trainers will be awarded an Ultra Unlock that will happen after the event ends.
Ultra Unlock is divided into three parts, Time, Space and the last part is yet to be announced.
Ultra Unlock Part 1 Time – Completed
The first part will be available if Trainers complete eight global challenges. If this happens, starting from Friday, July 23rd, at 10:00 a.m. Trainers will have encounters with Pokemon from various eras like Porygon, Cranidos, and Shieldon. This first Ultra Unlock is called Time.
Ultra Unlock Part 2 Space – Completed
The second part, called Space, will take place from Friday, August 6th to Tuesday, August 17th only if Trainers complete 16 global challenges. This part will reward Pokemon from various places.
Ultra Unlock Part 3 – Completed
The last part and the least part we have information on will take place after Ultra Unlock Space, and that is from Friday, August 20th at 10:00 a.m. until Tuesday, August 31st at 8:00 p.m. This part will be unlocked if Trainers complete 24 global challenges.
Which Pokemon do you expect to see during the third Ultra Unlock part? Hoopa or Arceus?