Route 95% of traffic to 1 pool and 5% of traffic to another pool.

You can do this via an iRule on a random basis.

when CLIENT_ACCEPTED {
  if { [expr { rand() * 100 }] > 95 } {
    pool <other pool>
  }
}

Sounds like Ratio load balancing.
But that's at the pool member level, not sure if you can do it at the pool level.
I've only ever done pool to pool stuff for failover.

Hi,

1. In this case you have BIG-IP DNS, You can specific load balance method ratio for distribute traffic 95% to PoolA and 5% to Pool B

2. If you don't have BIG-IP DNS, So i think you have to create irules for thie scenario