Lets se if we can clarify. You would like to translate two internal IP addresses as shown and all others (0/00 as shown?
So it seems like what you need is STATIC NAT for:
rule 1
172.16.0.56 --- > 200.55.125.153
rule 2
172.16.0.57 --- > 200.55.125.222
source NAT rule 1
and source NAT for with a pool for 200.55.125.156:
0.0.0.0/0 ---- > 200.55.125.156
You would use filtr-based forwarding when you want to forward traffic to a destination IP when matching criteria x.