In my company, we've 10 different teams. We are doing cutting-edge work in our niche. We use git repos, we extensively discuss things on Slack then summarize stuff in large paragraphs in Discourse. Then we commit the code to GitHub, our discourse bot adds links to the relevant discourse discussion in git commits.
Our teams have some guys who are difficult to work with but they've lots of talent. So, we've given them space and time. Sometimes, they do not like to take part in the discussion but it's important that they explain their thought process in Discourse.
This process reduced the time it takes to the onboard new member.
Most of the new members are already familiar with Slack, Discourse and GitHub UI. Search is just good enough, bot makes it easy.
For prioritization, we maintain slim Trello board. We don't use it much.