I'm a little late replying, but better late than never.
A suggested "VM Rightsizing Report". Although it's not a perfect report it can quickly show you info that you can use to i.d. vms that need to be upsized or downsized. to create the Report use:
Base Report Pack >Object type Virtual Machine.
For the columns I use Name, Runtime info: Boot time, vCPU count, Runtime info: max cpu usage, Memory: Amount (MB), Runtime info: max mem usage, Partition: Name, Capacity total, Free space.
The idea of the report is that i can see what VMs haven't been used in a while and are even powered off, compare the provisioned cpus and amount of mem to the actual max usage values, and see if the disk space allocated is enough or too much.