Here are the top colleges for BCom in Indore:

GOVERNMENT MAHARANI LAXMI BAI GIRLS PG COLLEGE, INDORE

M.B. KHALSA COLLEGE, INDORE

DAVV MATESHWARI SUGNI DEVI GIRLS COLLEGE, INDORE

DEVI AHILYA VISHWAVIDYALAYA, INDORE

PRESTIGE INSTITUTE OF MANAGEMENT AND RESEARCH - [PIMR], INDORE

ISLAMIA KARIMIA COLLEGE - [IKC], INDORE

CH INSTITUTE OF MANAGEMENT & COMMERCE - [CHIMC], INDORE

ALTIUS INSTITUTE OF UNIVERSAL STUDIES, INDORE

You can study for CAT/GMAT from any online programs that are available. For GMAT, Magoosh, Kaplan, Princeton test prep have pretty decent plans. Check out details on their website. Same applies for CAT too.
Good luck!