The New Batman Adventures, basically the sequel to Batman the animated series, they went with a more simplistic style based off of the style used Superman the animated series, it's also the same design they used in a 2003 static shock episode, the same year in Justice League they made her more green. but it's more or less the Definitive DCAU version of Poison Ivy as it's the most Memorable and most episodes of, unless we refering to the old style which makes her look like a 1940's pinup girl which isn't a bad thing either as it's a stark contrast with the original harley. But for all intents in purposes that is THE DCAU Poison Ivy, as it was the most seen version. also there's a collectors model based off of that design the Eyes are that pale green.
Also Batman the Animated Series only had 2 seasons anything after was the New Batman Adventures.
for what ever reason the first image shows as broken to me but when I pull it up in edit or go to the link it's perfectly fine, maybe the forum just doesn't like Gifs.
Edit: Changed the Image host to fix it.
Edit2: Funny enough the First Episode of The New Batman Adventures is a Harley Quin and Poison Ivy Episode.