I've never worried about moving powered off VMs via PowerCLI... Typically I patch via PowerCLI and the VMs migrate via DRS and anything left is unavailable for about 30 minutes at most.
If that doesn't work, going along the route of doing it manually may work too... You'd need to script disabling DRS, moving the VMs, and then setting maintenance mode. Finally, you'll want to re-enable DRS again.
This post from Damian Karlson for way back may get you started.
Ghetto host evacuation: PowerCLI — DAMIAN KARLSON