A friend of mine played it with swalot CG and crogunk. It's a nice idea, but really not powerful enough. mega isn't that powerful unless you are playing a fire deck, but any good fire deck would kill mega's face.
I used this line in mine 4-3-4 and teched in 2 delta versions 3-3-1x Lucario 3 Celebi Im not sure if you want to go into the fighting side with it but the pokemon line performed really well.
or may be u can hav some sunflora inside ur deck? but mega in dp form isn't tat good, wat i think is,it can be a tech in mega(d) deck.......
Venomoth is very nice, but Ariados is also nice! I understand it increases your retreat as well, but the Status stacking on them with an added retreat is just nasty! Also, I would take a Gander at Parasect. It also provides status for G and is a nice back up hitter for resetting!! GL and definitely 1-2 Meg D as it sets you up faster!