Do consulting companies need market research information? Or, is the market research information business of large consulting companies outsourced?

Often not.

For this problem, it can be understood that consulting companies actually include market consulting, that is, market research (research) companies. Consulting companies other than research companies often want to show their strong strength. Therefore, research, whether professional or not, is often done by oneself, whether professional or not, can solve the problem. So, generally speaking, they will not outsource!