Hello Dear,
if you want to tag the Native VLAN you have to use the command
"vlan dot1q tag native"
but if you dont want to use this command then there is only one option left and that's to change your native VLAN on a Trunk interface, by doing so your native vlan will be the one you specify and will not be tagged but then the vlan 1 will be tagged as its no longer the native VLAN. Remember that only Native Vlan is untagged.
The configuration that you have done will make the interface GigabitEthernet1/25 a static access port. And specifying the Switchport Trunk commands will not have any effect as the interface will never become trunk unless you change the mode to dynamic desirable or trunk.
If you are connecting to another Switch and Gi1/25 is the port you are using then the following configuration will Tag VLAN 1
interface GigabitEthernet1/25
sw trunk encap dot1q
sw mode trunk
sw trunk native vlan 777
This way the sw will become trunk and will tag VLAN 1 as it no longer is the native vlan. Remember that Vlan 777 will be untagged and you have to do the same config on the other end of the switch port also, otherwise it will give you a "native vlan mismatch error" and communication can be affected
If this interface is connecting to a PC then you will have to use the "vlan dot1q tag native" command. Theres no other way you can do it in this case. And use the following config on your port
interface GigabitEthernet1/25
sw mode access
sw access vlan x
Remember that in this case the "Switchport trunk ..." commands will have no effect as it is a Access port and not a Trunk...
HTH
Regards
Rohit