If "Flare Effect" or "Aqua Effect" or "Electric Effect" has added {R} or {W} or {L} to my {G} Ariados' type, when I use its "Poisonous Nest" Ability to poison all Active Pokemon except {G} type, is Ariados poisoned or not?
Ariados is not poisoned, because it is still {G} type.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)

Relevant cards

Note: All applicable cards may not be listed below.
XY7_13
XY7_22
XY7_26
XY7_6