You can quickly move entire spaces between different teams and accounts. If you need to have a whole space placed in another Craft account, just add the desired accounts to the same Craft app you're already logged in:

Once you have all accounts in the same app, you can right-click (or long tap, on iOS) the space you want to move and choose to move it to a team under the desired account. 

Important: Please note moving spaces between accounts will cause shared links to break and comments will be lost. 

You can also Move documents between Spaces.