I guess Pakistan should diplomatically, strategically help China against this common enemy India. I mean Pakistan can assist China about their nature of war fare, their fighting capabilities, through high level of Intelligence gathering for our Chinese Iron brothers.
As Pakistan Army is the most Professional Army in the world and is quite expert and professional in fighting Mountainous warfare and so we can also guide how Chinese army shall place their troops in Doklam to attack our common enemy india mean Chinese PLA is also professional army but we can give some prior suggestion how to place their troops on Hills/Mountains and how to take positions and to attack this common enemy if you are facing higher/lower mountainous terrains such as at most common places Doklam, Sikkim.
In the end, I would say China Army PLA is Professional army and knows better how to crush and teach same humiliation and defeat lesson to India just like of 1962 to India if they didn't back off their troops from the Region/area which belongs to China.