If I have an Ariados with "Sticky" Poke-BODY on the bench and another one as my Active Pokemon, does the Active Ariados have +1 added to its Retreat Cost or not?
Ariados' "Sticky" Poke-BODY should say, "The Retreat Cost for each player's Pokemon (excluding any Ariados) is {C} more". So Sticky prevents adding +1 to *ANY* Ariados' Retreat Cost, including your opponent's Ariados. Keep in mind that this does NOT include "Dark Ariados", just any Pokemon named "Ariados".
Source: PUI Rules Team (2008-02-21), Organized Play News (2008-02-28)

Relevant cards

Note: All applicable cards may not be listed below.
DP2_20