Which state are you from Ray?As for AIIMS,they will definitely suffice,but the problem will be biology,these days AIIMS biology papers are getting increasingly difficult,they expect 12th standard students to know difficult things like action potential and stuffs.Get some basic physiology text book for first year medical students(Ganog`s Text book is excellent)and read those chapters on action potential,NM junction etc.If you are well prepared for IIT,physics and chemistry wont be the problem.BTW read cardiac cycle from Ganog,it is very important.