Although you have an average academic record in 10/12, assuming you are from General Category I still believe you can get a call from either of IIM A B C , with a strong score in CAT (99.7+) , an excellent academic record in Graduation, followed by a great GD/PI and WAT.

For more information about CAT do follow the link below

https://bschool.careers360.com/exams/cat

For more information about the admission procedure of IIMs do follow the link below

https://bschool.careers360.com/articles/iim-admission-criteria