A good question dear svksanjan -- but it would probably require several volumes to really enlist and explain at any length Gandhi ji's role in the freedom movement, broadly.
However, to give you a basic sense or direction which you can follow up via your own research in libraries and online resources:
1. The MOST notable aspect of Gandhiji's role/contribution is that he was above mere communalism, and that he spoke a 'universal' truth, for all Indians, regardless of caste or creed. He was the only South Asian leader who kept on abiding by this principle until the end, 1947, even when almost all other leaders, on all sides , had succumbed to communal hatred and violent trends as a result of Partition. This fact alone places Gandhi ji head and shoulders above everyone else.
2. The 'movements' you mention-- Non Coop, Civil Disobedience, Quit India etc-- are essentially only physical, practical manifestations of 3 'Gandhian' ideals, as I see it (i) to Under take Non Violent Protest against the British Raj, to achieve India's freedom (ii) to try to 'carry' as many Indians, from all parts and of all castes and creeds, along, in an 'inclusive ' manner in the larger freedom struggle and (iii) come to amicable conclusions and solutions, to promote peace and love between all people, even the colonisers and colonised. A 'saintly' approach perhaps? It was certainly very different to the attitudes of various leaders of the Indian struggle and such freedom movements elsewhere--and in time also inspired someone like Nelson Mandela to emulate these ideals.