I'm not sure if it's harder to come up with new concepts for all the clubs in the different schools or new concepts for everyone having a different brand of table tennis.
I would imagine the latter would give them a tougher time to come up with. If you're going as far as using nuns as a concept for a team, then your options become endless from that point on for creating concepts for teams. You can have a maid team, waitress team, fortune tellers team, cooking team, even a cheerleader team that plays ping pong competively heck a cheerleading team would probably even help them create a concept for table tennis with using their cheerleading experience as a base with all their gymnastic cheerleading routines to create their own unique kind of table tennis.