Dear Syed ,  you have mentioned in your question about different  :entrance exams. These different exams have different eligibility

So , following are the exams and their eligibility:-

1. NEET :- Its eligibilty is that you should be a subject of India , a NRI , PIO i.e a person with indian origin and foreign nationals. Must have qualified class 12 with PCB(Physics , chemistry , biology/Biotechnology)  subjects

2, CET:- Its eligibilty is that you should be a subject of India , with min 50% aggregate in 5 subjects in 12th class.

For KCET , you must have done minimum of 7 years of schooling in karnataka.

3. COMDEK :- Its eligibilty is that you should be a subject of India and have atleast 45% aggregate in PCM. Diploma holders are not eligible.

So based on these , you can decide whether you are eligible or not