In case of lab environments the best method is to create Nested ESXi VMs.
This can be accomplished easily by creating ESXiVMs with the GOS as ESXi 5.x. Wrote a small script which does the same thing. There might be other ways of doing this like using autodeploy or using API to create the ESXiVMs at the first hand.
The following script creates 4 “ESXiVMs” with different names as mentioned in the “Name prefix”. VMs created will be “esxi551,esxi552,esxi553..”
NOTE: NESTED ESXi is not supported by VMware.