Does my opponent get to take a prize if I use Golduck's "Entangled Dive" attack to discard each player's Active Pokemon?
No neither player takes any prizes; Entangled Dive doesn't count as a KO.
Source: Astral Radiance FAQ; TPCi Rules Team (2022-05-26)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH10_29
SWSH10_29