If you are looking to move players from one team to another...
From The Mobile App:
1. Select the team you want to add players to from the drop-down teams list
2. Hit the 'Add Player' icon and select 'Copy Players'
3. Click the team you are looking to add players from
4. Press on the players you want to copy
5. Press Copy
From The Web:
1. From the teams tab, select the team you want to add players to from the drop-down teams list
2. Press the 'Add/Import' Button and 'Copy Players'
3. Select the team and players (with contacts) that you want to join your new team
4. Press Copy
The player will now appear on your new team.