We don't have a specific feature to move a team board to another team yet. But here's what you can do to move a team board to another team:
First, move your team board to public. If you don’t know how to move a team board to public, click here.
Note: You'll only be able to move a team board to public if you are the Owner of the Team.
Now that you moved your team board to public, you can move your public board to any Team you want. Click here to learn how to move a public board to a team board,