I've got a less CGPA in 10th and 12th. Will it be possible to do MBA in IIM or other B-Schools?

To make up for your low CGPA you can try achieving a high CAT score. However, the CGPA must only be 50% or above to make the cut for MBA in IIM.

Admission in Masters (MBA) is based on last qualifying exam (graduation with a minimum of 50%, and work experience) and the entrance exam as well as the interview. Therefore, your graduation percentage matters for MBA. Elite B-Schools are: Indian School of Business (ISB), Hyderabad (accepts GMAT) Ja

Yes, your academics do matter a lot, but remember there are other things too which they will calculate to select whether you are suitable for the IIM or not like you CAT score, whether you have work experience or not, your GD and PI performance. And then they will aggregate the entire score and then

What is your CGPA? Please mention it clearly. Marks always doesn't matter.

You need to clear IPM for getting admission in IIM and if other B-Schools conduct some entrance exam then you need to clear the same.

If you have a great score in CAT, you will easily be able to get admission in IIMs and the other B-Schools. Target a college and read the admissions criteria thoroughly.