If my opponent KO's my Active "Robo Substitute", would I get the extra benefits from Terrakion's "Retaliate" Attack or Toxicroak's "Revenge" Attack?
Yes, you would. Even though Robo Substitute does not give up a prize card, it still counts as a KO'd Pokemon.
Source: TPCi Rules Team (2014-12-04)

Relevant cards

Note: All applicable cards may not be listed below.
BW7_151
BW7_66
XY4_102