Sulley has returned but he is up against a master marksman. Train never misses his target and Sulley isn’t all that quick as it is. These two factors will result in a very easy win for Train. He certainly hasn’t gotten rusty as the years have gone by. Train even has the legendary Rail Gun that he can whip out if absolutely necessary but I don’t think he will need it. He could win this fight without even using his gun. Train wins.