which components should be made as good as possible if we want to get into IIM BANGALORE with 0 work experience i.e. after Bachelors degree? Also tell the same for IIM Calcutta.
First and foremost, for IIMs (A/B/C) you need to score a very good percentile in CAT. Assuming you're a GEM (General category, Engineer and a Male), and have decent academic scores (i.e. 85% and above in your 10th and 12th and 80% and above in your graduation) your percentile should be no less than 99.4 - 99.5.
Now, coming to specific B-Schools. IIM C gives less importance to your past academics and more to CAT and further processes (WAT, PI). So even if you have a poor score in 10th / 12th / graduation (obviously more than 70%), you still stand a chance by acing your CAT paper.
IIM B on the other hand gives a lot of weightage to your past academics. Therefore if you're not someone with 90% and above in both 10th and 12th, you might face serious competitions and if you have a poor score then you might want to drop the dream of IIM B.
But you can still look for IIM A, as it is more balanced than IIM B and doesn't necessarily put that much weight on your past academics.
Hope this helps.