Hello Satyajit,
Yes good spoken English is required to get selection in iim's. Because in Indian corporate world English is adapted as a common language and also to deal with other countries also. So you should be proficient in English. India is not a country like china, Germany and japan which prefers their language the most. In india there are huge number of languages of different regions. All have come to a common ground and given English as corporate language.
Thank you
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