How to stop Pokemon Go seeing everything in your Google account
Adam Reeve discovered that by signing into Pokémon Go with your Google account, you give it full access to your Google account. Google’s help page says that this means “the application can see and modify nearly all information in your Google Account.” It also warns, “This “Full account access” privilege should only be granted to applications you fully trust, and which are installed on your personal computer, phone, or tablet.”
Breaking this down, Reeve notes that this means that Pokémon Go and Niantic can read your e-mail and send mail as you, access and modify your Google Drive documents, and access private photos that you may store in Google Photos, among other things. It’s unlikely that the developer will, but it’s something to be aware of.