In an open-for-all competition, it is imperative for us to ensure that the problems match CodeChef standards in terms of quality. The level of difficulty does not matter as much as the quality of problem statements and test data do.
All the problems have to be original.
We can restrict access to your contest for a set of usernames or a set of IP addresses. Such contests are closed contests and only available to those people whom you give them access to. These can be used for a targeted audience like your college/school club or a group of friends.
We do not publicize closed contest in any way.
The quality checks are relaxed for a contest that is limited to a closed group like an intra level college contest.
These contests allow more than one user to participate.
There is a separate registration required by a team for participating in a team contest (The team members should be existing CodeChef users).