Assuming no VMs, you would simply pin every container to specific cores, and never touch any core that you want unraid to have exclusive access to.
With VMs, you would isolate the CPU cores that you want the VMs to use from the OS and then do the above.
Note that it is basically impossible though to completely isolate containers from the OS, as the OS can if it needs to use any core that's not isolated to them.
If you really want to go hog wild, then you isolate every core from the OS except for say 0 and 1, then pin what you want your VMs to use and you could pin each container to a SINGLE isolated core. It is not possible in this circumstance to pin a container to 2 or more isolated cores and have it execute on any of them except for the lowest numbered one.