You can disable HA & DRS for specific VMs,
To disable DRS
Navigate to the edit settings of thecluster thenclick onvSphereDRS > Virtual Machine Options > Select Disabled for the specific Oracle VMs.
To disable HA
Navigate to the edit settings of thecluster thenclick onvSphereHA > Virtual Machine Options > Disable VM Restart Priority, this will disable HA for that specific VM.Also youcan configure the Host Isolation Response to leave PoweredOn.
You can also view this other posting discussing the same thing: https://communities.vmware.com/message/2283060