For Admission in MBA college You have clear the CAT exam with a good percentile in it. Also, you have to maintain a good record, Also to get into top IIMs, you have to secured more than 99.5+ percentile, then you will be definitely get a call for the top 3 IIMS, that is IIM Calcutta, IIM Bangalore and IIM Ahmedabad.

After the declaration of the result the merit list will be made  to call the candidate for the interview round.The merit list comprises of your CAT percentile, your graduation marks, your work experience, your 10th and 12th marks. Also, if you have secured more than 95+ percentile, then you get call from the others IIM for interview and Written Aptitude test. As you have If you have score above 98+ percentile i.e IIMS ,you will have a good probability of getting calls from old IIMs like IIM Lucknow, IIM Kozhikode, IIM Indore, IIM Shillong.

Once you get call from IIM, you have to go through the WAT exam and interview process. On clearing both an another merit list will be prepared, which will select you to get enter IIM.