When copying a virtual machine (VM) from on datastore or other VMware instance, you will need to add the copied VM to your ESXi inventory. To do this is not entirely clear, at least no to me. A lot of the postings I saw on this did not make it clear, so I want to get this down while I remember it.

Copy the VM to one of your datastores (i.e. /vmfs/volumes/datastore1/ ).
Once the VM has been copied or moved, you will need to bring up the vSphere client.
Select your ESXi instance in the left panel.
Click on the Configuration tab.
Click Storage under the Hardware section.
Then, right mouse click on the datastore that you just copied the VM to, and click Browse Datastore.
This will bring up a window that will display all the directories under /vmfs/volumes/datastorex.
Drill down into the directory where you copied your VM and select the appropriate configuration file ( .vmx ).
Right mouse click on the configuration and select Add To Inventory.
This will run you through a small wizard procedure to name the VM.
Once completed, you can power on the virtual machine, by right mouse clicking on the VM and selecting Power On.
Note: Because you copied or moved the VM, when you power the VM for the first time, you will need to switch to the console and chose the appropriate option (copied, moved or cancel).