I have 95 percentage in class 10 , 82.4 in class 12, 9.8 CGPA in BTech Marine Engineering, if I get above 98 percentile in CAT can I get into top IIM ?
Congratulations on your great academic records. But sadly that will only give you an added advantage but will not guarantee you a seat in top IIM. Also you have mentioned top IIMs, but you have not mentioned whether you wish to persue MBA from the old ones like Ahmedabad,Bangalore,Calcutta or the comperatively newer Lucknow,Kozhikode,Indore.
Sadly if you are general and you being an engineer, you need atleast a 99.2+ %ile to get into any of them along with performing exceptionally well in WAT-PI.
The diversity factors will help you in improving your overall score and also help you in your interviews (I believe), but you need a very high percentile to get admission in the IIMs.
Hope this helps!