who plays tiffany thornton, david henrie, sterling knight, joe, nick, and kevin jonas, zac efron, vanessa hudgens, ashley tisdale, emily osment, miley cyrus, sam droke, meaghan martin, alyson stoner, bridgit mendler, cody linley, chelsea staub, nicole anderson, jake t austin, taylor swift, and mitchel musso that would want to join a psl group