If I have a Poliwrath on my bench that evolved from a Poliwag and a Poliwhirl do I get all of the damage bonuses for each of them?
No, you only look at the most evolved stage of a Pokemon in play. The previous stages are now part of that Pokemon.
Source: Lost Origin FAQ; TPCi Rules Team (2022-09-08)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH11_32
SWSH11_32