Hmmm. You know how the scholastic team made a collage of a basketball player with Troy's head? Maybe the kids could do a collage. Put their own heads and/or heads of other party guests into different pictures. Or assemble collages with their picture & different things that they're interested in. You cut out a bunch of photos from magazines & catalogs-- sports gear, books, music, animals, etc. I find these kinds of crafts are good for kids to do at the beginning when you're waiting for everyone to arrive. The early kids can keep busy & get in the mood & later kids can either do it quickly or skip it.
you can decorate (or order) the cake as a basketball or a record/CD
decorate the room in Wildcat colors (red & white)
learn some simple cheers
do a bean bag toss that's set up like making free throws
invitation could be written on music paper
or could be written as if from the principal, ordering the child to show up at a certain time and place for "detention"
definitely serve chocolate chip cookies!! or those could go home as a party favor the way that Zeke gave them to Sharpay
maybe give out mini Sharpie pens as party favors too!? Sharpay's name always makes me think of Sharpies!
the kids could all write a hobby that they do that the other might not know about. put these in the middle & mix up, then guess who does what hobby (inspired by "Stick to the Status Quo") if not a hobby, then a book that they like.
maybe online you could find a quiz "which character are you?" or make one up.