When upgrading to Trello Business Class, consolidating teams is a good way to unify your users and boards so that you don't pay multiple times for each user.
If you don't have any teams upgraded to Business Class, upgrade the one with the most members. Otherwise, select a Business Class team. You can change a team's name and short name at any time by clicking “Edit Profile” from the team page:
“Name” is what will appear on that page, and “Short Name” is the string that will show up in the team’s url (e.g. trello.com/teamname).
Once you've upgraded that team to Business Class, check to make sure Guests are allowed on team boards from the team’s “Settings” tab:
From that team’s Boards tab, create a new collection for the first team you’re going to merge:
If you need to edit a collection’s title or delete it, click the “+” icon under one of the boards and the pencil icon next to the collection you’d like to edit:
Once the collection is created, go to the first team you’re going to merge. If there’s an option, click “Show other members’ personal boards” so you can be sure to move all boards over. This icon won’t show up if there aren’t any private boards you’re not a member of:
If you’re moving over a board that you don’t want everyone to have access to, be sure the icon on the far right of the title says “Private”:
If it says “Public” or “Team-visible”, you can change the board to “Private” by clicking that phrase and selecting “Private”:
Once you’re ready to move the board, click the name of the board’s current team directly to the right of the title and select “Change Team”:
Select your main team from the drop-down. Once the board has been moved, you can add it to a collection from the mean team’s boards page. Click the “+” under the board:
Once you’ve moved over all boards from a team, you can move over the members. Go to the team you’re merging to find the usernames of your team members:
On the main team, click “Add by Name or Email” to add this member:
If you’re unable to click the member to add them, they are already a member of the team:
Then, go back to the team you’re merging and remove that member from that team by clicking “Remove” to the right of their name, to keep track of who’s been added.
Once everyone has been added removed from that team, you can delete it. Go to the Settings tab and click “Delete Team?” to remove the team from Trello.
Continue these steps for your remaining teams.