Points of My Scenario:
1. I am admin of a single vCenter instance (version 5.5) supporting 6 clustered ESXi hosts (ESXi 5.5 U3) and 4 standalone ESXi 5.5 hosts
2. I must replace all clustered hosts with new, upgraded hardware with a higher processor architecture.
3. Objective A: implement a new, un-linked vCenter 6.5 instance on the new hardware
4. Objective B: deploy six new ESXi 6.5 hosts in a cluster on the new vCenter 6.5 instance
5. Objective C: migrate the four standalone (un-clustered) ESXi 5.5 hosts into the new vCenter 6.5 instance
6. Objective D: migrate all VMs from the old vSphere 5.5 cluster into the new vSphere 6.5 cluster
QUESTION: Regarding Objective D - how can I VMotion (or otherwise migrate) virtual machines from one instance of vCenter (5.5) to a completely separate instance of vCenter (6.5)?