Officially HA is suppose to move the offline VM's as well if a host unexpectedly goes down.
So make sure HA is setup correctly (with HA datastores ect) and if all is working as it is suppose to (a few bugs have got us before and items did not move as expected, but support should be able to help with that) the offline VM's will move one the powered on HA protected VMs have been moved.
I was trying to find some more details on this process of catalog protection from VMware, but I can't seem to find anything. (Hoping someone from VMware can post a link to a KB or whitepaper that goes into some detail on this)
