Check the 3d Model: sketchfab
also this tutorial: https://www.youtube.com/watch?v=2FsNBJaseNI
Set me on the right path.
This is the original concept that I sketched, to get an Idea of what pose I wanted gengar in.
This is the progress of the model so far, I've got the texture done for mega gengar, but now am trying to figure out how to make the shadow ball effect.
I've found some tutorials on particle effects in 3ds max, so am going to go from there, and see where it takes me.
This thread here looks promising: