Q: Can I migrate services from my Windows Server x cluster to aR2 cluster?
A: Microsoft provides an n-2 cluster migration support. This means the migration of clustered services is supported from two versions back.
This means that for a Windows Server 2012 R2 target, cluster then services can be migrated from Windows Server 2012 clusters (n-1) and from Windows Server 2008 R2 clusters (n-2). It's important to note that migrating cluster services doesn't copy storage--when migrating services, the cluster storage is moved from one cluster to another. Only the resource configurations, which are effectively registry values, are moved from the source to the target cluster.
If you have an older cluster, for example Windows Server 2003 R2, and want to move to Windows Server 2012 R2, then one option is to stand up a temporary Windows Server 2008 R2 cluster and use that as an interim hop for the migration of services to Windows Server 2012 R2.