The number of vCPU's depends on your ESXi host, either your limited to 8 or you will have 16, 32, etc. The vCPU amount is defined on the VM or PI2.0 and you can change it after the VM has been installed. PI 2.0 has an Express (4 vCPU), Standard and Pro which require 16 vCPU. There is a custome express that uses the Express ova (4 vCPU), but you need to increase that to 8 vCPU. Hope that helps.
Help out other by using the rating system and marking answered questions as "Answered"