How will you ssh into some Other system's root account?

That is actually the proper way to SSH into a server (192.168.xxx.xxx), that accepts SSH connections on the default port (22). To specify the user you want to use for login, you can use:

ssh -l root 192.168.xxx.xxx

or

ssh [email protected]

If the SSH service is configured to allow root login, you should be able to connect without problems (PermitRootLogin yes, under sshd_config).