so that mean only one type connection pooling is recommended either application side or database side using PgBouncer .
That isn't what I said. Given that you provided zero details regarding your environment I will not make any specific recommendations.
How good could be using the PgBouncer If data is coming at the rate of 200 MB/hour , And there need about 100 concurrent connections for read purpose .
Any solution is likely to operate adequately at 200MB/hour; and 100 connections - no matter how you define them - seems within its capability.