It was night time so wasn't enough light for my camera... ANYWAY! Soloed Fistule as DNC/MNK just about all fistules for my discharges although I did join up with parties very few but managed to finish 80 Gandiva!
Yes, the quality was bad on my camera at night and stuff but who really cares :p. I started working on the fistule discharges right when I first started the bow trials, trying to work them up both ways. I was looking on wiki on how to solo fistule and tried DNC/MNK using Fan Dance and Counterstance. Atmas used were Gnarled Horn, Razed Ruins, and Apoc. As stated above, I did team up with a few parties on the way doing this, but this was mostly done solo.
The simplicity of the Gandiva first stage is more than made up for in the absolute craptacular second stage. Good luck, Bukhis is one of those NMs that SHOULD be easy (and can be), but that you'll never be able to trust a PuG with. Always have a plan.