Matt's Zuko and Druk would have been in attendance, in some of their Fire Lord Finest. He would have congratulated them and wished them well, but it's probably still obvious that he's not over losing most of his friends recently.
Iris very likely attended with the Chocobros, looking great in something appropriate and enjoying the drinks. She got them an obligatory blender, you're welcome.
Jin Ling was of course there and was immensely proud of his uncle and showered them with praises as befitting the Jin Master.