How to Restrict a user, not a root, Login to the Console?

I need a restrict user (oracle for exemple) login to the console. With a superuser root, edit the /etc/default/login file, but with a user???? 

I want that any users who try to remotely log in to this system must first log in with their personal user login, and then use the su command to become a application user.

I'm working on Solaris 8, and don't want implementation a RBAC solution.

Any assistance will be appreciated.

Regards
Cris