Hello Khushi

There is no where mentioned anywhere that any IIM's has their eligility criteria which includes the perecentage of 10th as well as 12th. But as you know being best in b-schools IIM A or IIM B will not consider anywhere below 90 or 95 in 99% of the case unless you have any very special  few extracurriculars or certificates or profile diversity.

So, to get into IIM A or B you must have atleast a percentage of above 90.