Tron would love to help fight the Hulk! He's got a lightjet (with lasers!) at his disposal now, along with disc weapons. Pretty sure the Hulk would just swat them down, but hey, he could be a good distraction. :)

ALSO ALSO if we want to make things extra-complicated Tron can have his own dark side come out during the fight and you can have Rinzler "helping".