I buddy box Futaba's just about every weekend. You do not need to remove the battery or crystal. You do need to keep the slave transmitter turned off so it will not actually transmit. You can not use the dual rates, mixing or exponentials if equipped. You do need to check and correct any servo reversing as needed. Check trims like John Buckner said and if changes are made after takeoff it may be wise to have experienced flier trim slave box for you. This should work for you.