Aviation

To be medically fit, you need to hold 2 medical certificates. Class 1 and Class 2 medical certificates. First of all, you have to get the Class 2 medical certificate, and if you are found medically fit in that, then you apply for the Class 1 certificate. I'm in class 12th, so you need to wait until you clear your boards. To apply for a class 1 certificate, you need to pass 10+2 boards. To have a class 2 certificate, you need to get these tests done.
Blood group (ABO & Rh), Hb, TLC, DLC, Urine RE (with ME and Sp Gravity) from NABL/NABH accredited lab/hospital. X-Ray Chest PAECG-Resting.
Audiometry and opinion of the ENT specialist. The opinion of the eye specialist. If a close family member has Diabetes/Hypertension/IHD or there is a history suggestive of kidney stones in the candidate additional tests may be required. If the BMI is 25, Blood sugar fasting and 2-hrs after 75 gm glucose, and Lipid Profile would be required. On spot, BP check and full body examinations are done by the doctor.
Good luck.

The usual profile for a fresher is as under:
Age: Between 18 and 27 years.
Minimum Height: Men - 170 cms and Women - 157 cms.
Weight: In proportion to height.
Educational Qualification: HSC (10 + 2). Candidates who are appearing for their HSC examinations can also apply.
Physical features: Pleasing personality, clear complexion (scars, pimples and blemishes not acceptable) and good eyesight.
Marital Status: Unmarried.
Language skills: Fluency in English and Hindi. Proficiency in a foreign language will be an added advantage.
Interactive skills: Excellent communication and good interpersonal skills.
Nationality: Indian citizen.
Passport: Must possess a valid Indian passport or should have applied for a passport.
Mandatory Documentation: Must possess a Pan Card and Aadhaar Card.
The training institute shall guide you further for the interview. It is not at all expensive to pursue the dream of becoming a cabin crew. All you need to be is personable, presentable, good in communication and outgoing. Additional advantage can be gained if you know some foreign language.
Go ahead with it.

Yes, you can. The organisation shall take care of all your training and initial requirements. The selection process is as mentioned under:
Only those who pass a rigorous assessment and selection process are offered a training place as a
cadet in one of IndiGos aviation and airline programs in India or worldwide. The entire process of selection consists of a Math, Physics & English written, psychometric
evaluation, a Group Discussion/Group Task and finally an individual Interview. This process is designed to discover your potential to become an airline pilot and is, in effect, your
first step to the flight deck. Our aim is to discover:If a career as a pilot is really for you. Do you have what it takes? If you have the Aptitude and Attitude to succeed during your training and beyond. Qualitative Requirements are as follows:
The first step in this direction will be to obtain a Commercial Pilots license more commonly referred
to as the CPL, followed by the Airbus 320 Type Rating (A320 TR); combined the CPL+A320 TR are
the very foundation of your flying career with IndiGo. Please review our minimum entry requirements to qualify:Aged between 17 and 30 years and of Indian nationality or an OCI card holder. Achieved a minimum score of 55% in Physics, Mathematics & English in 10+2 exam (if an
applicant has graduated with Physics and Math or Engineering with a mark of 55% or more, the
eligibility criterion in 12th with 55%, except English, can be overlooked. Possess an Indian Class 1 Medical certificate (no limitation)*Be in good physical condition with appropriate weight and heightBe fluent in English both written and verbal. Have unique-ID number /registration number (UID) at the time of admission. *candidates not possessing an Indian Class 1 medical can apply for the IndiGo programme with a Class II
medical, however, they must possess an Indian Class 1 medical prior to commencing the programme.
Good luck.