This is very easy method to transfer tablespace from one database to another database by using RMAN.
Explanation: By contrast, when RMAN creates transportable tablespace sets from backup, it does not need access to the live datafiles from the tablespaces to be transported. This eliminates the need to put the tablespace in read-only mode. As a result, database availability is improved, especially for large tablespaces, because the tablespaces to be transported can remain open for writes during the process, and because putting a tablespace into read-only mode can take a long time, depending upon current database activity.
Oracle EBS apps Upgrade from 12 2 to 12 2 5 (start CD 51) : https://www.youtube.com/watch?v=zeO4goqR70Y
Transport tablespace by using RMAN.: https://www.youtube.com/watch?v=YG6kWX7Par8
Table Shrinking in Oracle Database : https://www.youtube.com/watch?v=bdockmBDvz8
Transporting tablespace to different platform by Using RMAN : https://www.youtube.com/watch?v=CN401PUKK4A