Pokémon Go ‘Go Big’ event guide
From Sept. 10-15, you can catch Kanto starters in Max Battles. We list out the perks and bonuses of the “Go Big” Pokémon Go event.
This article references relevant content from the polygon.com website. Original article link: [https://www.polygon.com/pokemon-go-guide/449799/go-big-event-field-research]

Pokémon Go’s first “Go Big” event is the first to introduce Dynamax and Max Battles to the game. It runs from Sept. 10-15 and introduces a few Dynamax Pokémon and serves as a bit of an intro to Max Battles before things may start ramping up.
The event also has two bonuses: doubled XP from winning Max Battles and doubled XP from spinning PokéStops. It also added more steps to the “Galar Calling” Special Research and the last step of the “To The Max!” research is now completable, since Max Battles have rolled out.
Below we list the other event details of the Pokémon Go “Go Big” event, including the event Field Research that you may find from stops.
Pokémon Go ‘Go Big’ event Field Research and rewards
Spinning a PokéStop during the event period may yield one of these tasks:
Pokémon Go ‘Go Big’ event Dynamax targets
These Pokémon will be in Max Battles during the event: