For client copies (any method) you need to make sure the BASIS release of the source and the target systems are same.
But if you are planning to perform transports across system with different BASIS releases then you should read this SAP note as there are certain combinations that are supported.
1090842 - Composite SAP Note: Cross-release transports
If you are sure that the objects involved in the transport request and the impact of that on the target system then you can move those transports to the target system and import them with the flag "Ignore Invalid Component Version" checked.
Again I am talking about the transport request and NOT client transport.
Regards
RB