What is the ideal rank/marks I should get for a descent college?

To get a good college your rank have to be with in 1500, to get a good college and of your choice the rank should be under 700.
Now about marks, nothing cannot be precisely said. As it depends upon a number of factors, if the question paper was easy or tough, cutoff and no of students. But according to the past years trend, to score rank under ,1500 one should expect marks above 630. So it will be a tougher deal, but it will be worth it.

The criteria for categorizing a college as decent or indecent is subject to an individual's opinion. Nonetheless, by decent, I'm assuming you're talking about the highly reputed colleges of our country.
It is very obvious that if the college is in demand, the competition to get into that college will be pretty high, irrespective of the field of endeavor.
Same is the case in MBBS as well. And in open category, the most renowned colleges generally get filled up under AIR 1500. Marks required to enter into such colleges range anywhere between 590 to 650 depending on the level of difficulty of the question paper.
I personally feel that, if one keeps in mind, the level of difficulty of the examinations and the amount of competition one has to face to get into a medical college, no college can be called unsatisfactory! Every college is good, because it all depends on how you handle what you've got.

Hey!
Getting into a good college requires very high scores which can only be achieved by sheer dedication and hard work. There are various criteria for ranking.Your category also is very important criteria for ranking.
General category has more struggles because other categories have reservations.
Focus on your weak subjects. People mostly neglect physics please don't do that. Be clear with your concepts. Solve previous years question papers.
Follow the 3R's READ REVISE REPEAT.
Revision is the key to success and for physics practice the questions. Prepare a timetable and stick to it. Scoring high is easy in biology. Be perfect in that subject. Everything should be on your fingertips.
Along with studies maintain your health too.
Harshita Jain (CR@campus career)

Depends on what you are aiming..a all india rank of top 200-500 for best 10-15 colleges..an air of 2000-3000 for all india decent colleges..
State rank of top 200 for best state college seata..top 500 for decent college seats in government colg..
However will depend from state to state..better check out the seat matrix of different colleges in your state on the net for further helo..