Feels similar to how players like Roberto carlos, Dani Alves etc are great at attacking from full back position but would not do well in winger position.
Like Pant's attacking ability is better suited to the more patient approach Tests and ODIs than the aggressive T20s...
Ya it basically comes down to the fact that Pant needs a few balls to get used to the pitch and then he can cut loose. I feel he can improve on being able to go from ball 1 but there really isn't a player out there who can consistently do this apart from maybe Andre Russell.
The bigger issue for India is the top order being so unreliable at the moment. Kohli needs to be dropped immediately, think the off-pitch activities have gotten to him as he plays like he's distracted. The idea of Shaw and Gill is not bad, although it's time to put Samson in the T20 team, thought he had a very good IPL and like his SR coming into the early middle order. Here you go for T20: Rahul, Shaw, Ishan, Samson, Hooda, Pant, Hardik, Jadeja, H Patel or Arshdeep, Bhuvi, Bumrah. You get a great balance of right and left-handed batsmen throughout the order. It would be hard to leave Rohit out but I think you would only want one of Rahul or Rohit to play anchor. I would also bowl the last 3 overs with Arshdeep, Bhuvi, Bumrah who are all great at the death. This team would win the world cup but it will never be selected.
For ODI it would be Rohit, Shaw, Gill, Suryakumar or Samson, Pant, Hardik, Jadeja, Bumrah, Shami, Chahal, Siraj or Prasidh Krishna as it's useful to have more bowlers for this format.