It is possible to set virtual machines to automatically startup and shutdown with the ESX server.
You may want to do this for example in a test environment where vCenter is in a VM.
Rather than connecting to the ESX server and starting the vCenter VM then connecting to vCenter, you could connect straight to vCenter.
Click on the "Configuration" tab of the ESX server and go to the "Virtual Machine Startup/Shutdown" section.
You will see the VMs are set to manual startup.
Click on "Properties".
Check the box to "Allow virtual machines to start and stop automatically with the system".
Set the default startup and shutdown delay.
If VMware tools is installed you can set the guest to shutdown gracefully rather than just powering off.
Select the VM you want to auto start/stop and click "Move Up" so that it goes to "Automatic Startup".
An overview of the configuration can now been seen in the "Virtual Machine Startup/Shutdown" section.