1. Change PermitRootLogin to yes in /etc/ssh/sshd_config.
  2. Comment out the CONSOLE=/dev/console” in /etc/default/login.
  3. Execute rolemod -K type=normal root
  4. Restart SSH with svcadm restart svc:/network/ssh:default
  5. Done.

(credit http://veereshkumarn.blogspot.com/2012/09/how-to-enable-ssh-root-login-in-solaris.html)