Hi Devanshi,

Admissions to the IIMs are only done through CAT scores. However, many top colleges also accept scores obtained in ATMA, XAT, MAT or GMAT. Some top private intitutes hold their own entrance examinations e.g. Amity, NMIMN, Symbiosis, XUB etc. If you want  to take direct admission without giving any national level entrance test, some institutes, which are not in India's top 100, also offer that.