At PokeTube we do not collect or share any personal information. That's our privacy policy in TL;DR. To improve our products we had to create a completely anonymous way to figure out how PokeTube is being used.
We use a tool called Piwik (A free software Web analytics system,see piwik.org) to collect information. By information we mean, aggregated data about things such as the number of visits daily/weekly/monthly to PokeTube. Learn more on our privacy policy.
You can see the source code of this, here : on GitHub.