if the new hosts have access to the iSCSI storage, i.e. the current datastores, you can simply shutdown the VM's, remove them from the old vCenter Server's environment, and add them to the new one.
Depending on the new hosts' configuration, you may need to reconfigure the VM's network (port group). What you may do, is to create a temporary snapshot prior to powering on the migrated VMs (just in case something unexpected happens), install/update VMware Tools, and upgrade the VM's virtual hardware.