Is there a way to allow the VM's to communicate when on different ESXi Hosts so that we can make use of the Cluster and it's resources? This Internal Network will probably consist of near 100 VM's which is why we are trying to utilize the Cluster.
No, that isn't how networking works. In order for VMs to talk across ESXi hosts, they have to traverse a network, which means there has to be uplinks to route them to the physical world, and there has to be networks which live on the physical world to move packets. There are a variety of ways to go about this, probably the most common simply being a VLAN with no gateway, but you must have physical networks available.
Thank you for the quick response.
Would something like this be possible with NSX?
Even with NSX, you still have to have an underlay network (physical network(s)) over which to carry the overlay traffic. There's no way to get around the need to have a physical network connecting physical ESXi hosts.