What should be your qualification to become a pilot?
Minimum 10+2 (HSC OR 12TH) With physics and maths or equivalent (diploma)

What should be your age to become a pilot?
You can start early but should be of 18years to get you CPL.

Medical fitness requirement to become a pilot
There are two medicals done CLASS 2 and CLASS 1.
You do not require a muscled body to become a pilot in India but however you should be fit from head to toe. So for this directorate general of civil aviation has appointed doctors all around India for that.
First..!
CLASS 2 medical is done. You can directly contact an approved class 2 doctor list of them is available on dgca.gov.in. After you are done with medical you will receive a pmr no. also known as file no. for your future references. After getting that PMR number you can apply for CLASS 1 medical to DGCA.
CLASS 1 medical is mainly done by the air force medical centers but there are few civil centres are available also.

What after medical?
Once the above conditions have been met, the candidate can enroll with a Flight Training Institute. There at the institution, the student must undergo a minimum of 200 hours of flight training which includes 100hrs as pilot in command. Most of this flight training is done on a single engine training aircraft. To get into an Airline or any other charter flying company, one has to get a multi-engine endorsement on your respective pilot licence. Well for some of you out there, it might look easy like just too fly like approx. 20hrs and get a job to an airline. But no, becoming a Pilot is not that simple cause after all you have to deal with different & complex situations every time you get in the air. Whenever you sit in a cockpit there is a new challenge to overcome. So to make sure that a pilot is fit and up to the best standards to deal with such circumstances the student is also required to clear five DGCA theoretical exams, namely
1. Air Navigation
2. Meteorology
3. Regulations
4. Technical General
5. Technical Specific

THESE EXAMS ARE CONDUCTED 4 TIMES IN A YEAR AT A GAP OF APPROX 3 MONTHS.
The candidate also has to clear a Radio Telephony (RTR) exam conducted by Government of India (MINISTRY OF Telecommunications) six times in a year. This exam as the name suggests makes a pilot proficient in the field of radio telecommunications as all the work which is done up in the air is dependent upon radio communication. On completion of above requirements, DGCA issues a Commercial Pilot License to the student.

What are DGCA exams?
DGCA Exams are not any entrance exams these are exams which every student pilot needs to pass for the issuance of cpl and you need to score a minimum of 70 marks in each subject.
How to apply for DGCA exams and computer number?
To appear for dgca exams a candidate first has to apply for a computer number for which he needs to have a valid class 12th marksheet with physics and maths or diploma marksheet. You need to do signup on pariksha.dgca.gov.in.
Once issued with computer number you can apply for the exams on the same website whenever the portal for exams is opened. Generally it remains open for a period of 7-10 days.

Things to be noted
You can clear DGCA exams prior to going to any flying school in India or abroad.
If flying from abroad and giving exams prior going to flight school you will have to appear for three exams Navigation, Meteorology and Air Regulations and after returning just skill test of 8-10 Hrs.
If flying from abroad and giving exams after completing your CPL from abroad you will have to appear for two exams composite (Navigation & Meteorology) and Air Regulations and skill test of approx 20 Hrs.
Computer number has nothing to do with medicals and they can be obtained after you have completed your 12th.

For more:- How to become a pilot after 12th ?

Source: pilotexams.co.in