Here's the Ultra Bonuses:
Week #1: Dragon Week:
When: July 31 4:00 PM EDT - August 7 4:00 PM EDT
If Trainers around the world complete 8 of the Global Challenges during Pokémon GO Fest 2020, Dragon Week will be unlocked.
- Dragons will appear in the wild and 7K Eggs
- Rayquaza in Raids

- Shiny Deino line will be released
Week #2: Enigma Week:
When: August 7 4:00 PM EDT - August 14 4:00 PM EDT
If Trainers around the world complete 16 of the Global Challenges during Pokémon GO Fest 2020, Enigma Week will be unlocked.
- Pokémon associated with Space will appear in the wild like

and

- Deoxys in Raids
- Shiny Staryu line and Deoxys will be released. Niantic specifies Normal Deo.
Week #3: Unova Week:
If Trainers around the world complete 24 of the Global Challenges during Pokémon GO Fest 2020, Unova Week will be unlocked.
When: August 14 4:00 PM EDT - August 21 4:00 PM EDT
- Sewaddle, Cottonee, and Emolga will appear in the wild and 7K Eggs

- Bouffalant will be an NYC Regional and in 5Ks

- Genesect in Raids
- Shiny Roggenrola and Shiny Genesect will be released
EDIT: Corrected info on Bouffalant being in 5Ks instead and Niantic specifying Normal Deo.
3500 Pokémon Storage is also now live.