Can I Migrate VM Network From Cluster 1 To Cluster 2

If I understand correctly, both VxRail clusters are connected to the same ToRs. In this case:

      You enable Vlan 25 on all the switch ports connected to cluster 2.

     Create a Port Group on the cluster2 vDS and assign Vlan 25 to it.

     Adjust the uplinks for the port group so vSAN links is standby.

At this point you should be ready to migrate VMs.

I am not migrating VMs.

I have deployed two VxRail clusters managed by one vCenter.

I defined guest "VM Network" named Apps (vlan ID 25) when I deployed VxRail cluster 1.

I want move "VM network" named Apps (vlan ID 25) from VxRail cluster 1 to VxRail cluster 2.

I am not sure what do you mean by move network.

Usually a Network it is a Port Group on the Distributed switch. You can't move it between clusters, but you can create the same on different clusters. The only thing I've seen is a name limitation - it has to be unique. Not sure if this is per data center or vCenter. But since you are "moving it", remove the Network on Cluster1 before you create it on Cluster 2 and it should be fine