Guwahati to Bangalore - is via Kolkata. Jet provides bassinet for babies less than 1 year old. Note: you need to buy a separate ticket for infants. We have not found any other airline in India which offers bassinet for domestic travel. It is on first come first serve basis, best to arrive at the airport 3 hours in advance. You cannot web check-in with Infant tickets.
If you need to choose any other airline, stick to Indigo.
We have travelled 3 trips between my kids age of 3 months to 6 months using Jet as well as Indigo.
Jet konnect flights may not have bassinets, so check before you book.
P.S. Only working solution for pressure change is - feed the infant during takeoff and landing.