I would say a club would have to:
Have three or more people, who agree to participate and be active within it.
Have an account on the Kokoro forums.
Determine the club objectives (IE: Spooky club that performs exorcisms? Book club? Raise awareness for a cause? etc.).
Organize a meeting location within Kokoro grounds, and a time (Maybe make an agenda/timetable and post to the forums).
I think there should be minimum members (as I wouldn't define a club as a duo), probably an event frequency (all participants agreeing on a frequency of meetings or social events, etc.).
I think there should be club themes, I'm not too sure on goals. It would have to depend on what type of club it is, like as an example, a gaming club's goal may only be to play games every week, while a fundraising club would be to raise awareness/raise funds for a cause.
Annnd I think it would be a good idea to check up on clubs to see if they're still active, see what they're doing, etc. No Deado Academy clubs!
Another thing I think that would be a cool concept is for clubs to be able to make flyers/posters and be able to put them up on notice boards, or maybe have a pop-up recruitment stand for their club. Maybe have their own Discord channel, own forum thread, be able to hold events where they showcase what they do and whatnot. A creative element would be fun, instead of just static meet-up, chat and repeat. 😄