IIM

You can check the eligibility criteria in the IIM Shillong website http://www.iimshillong.ac.in/admissions/pgp-admissions/#w349 . All the details are mentioned in the wesite.

Hi Damini,
It depends on your category if general 99+ would be enough. However, percentile is not the only criteria.IIMs look for overall performance and potential of a candidate apart from academics, there is a significant shift in the selection process from academic-centric to overall performance and capabilities of the students. The Cutoff percentile is different for different IIMs and it changes every year, you can get the report on official websites of respective IIMs.

The chances are good, but it would also depend on your academics and qualifications.

Yes, but you need to have minimum 50% marks in graduation to be eligible for it.

Determination, continuity and hard work in your preparation. Solve the problems in less time, practice as much as possible.

Check this link for CAT 2015 cut offs -
http://www.entrancecorner.com/bschool/cat-cutoff/
It was around 80 percentile for most IIMs.

To get admission in legacy IIMs is quite tougher in comparison to public sector Banks PO examination as competition is very high for legacy IIMs. But, toughness and competition will be similar for new IIMs and PO examination.

It depends on your preparation and interest. If you are interested in IIM and well prepared, it is easy but CAT is comparatively tougher than Bank PO.

Hi Vennela,
It depends on your category. If you belong to general category 99.8+ would be enough to sail through. However, Percentile is not the only criteria to get an admission but it is the first step. Interviewers judge your personality traits and gauge your capabilities in the interview before making you a final offer.
All the best

You need to clear entrance exams like:
1. CAT.
2. XAT.
3. MAT.
4. CMAT.
5. SNAP.
6. TISS.
You need to have more than 50% in graduation.