Reimagine Fx uses the Flight Node in Maya to animate multiple instances quickly.
One method for animation is to use MASH in Maya. The Flight Node in MASH is a great way to create flocking animation easily. The last few tutorials from Amar Shinde (Reimagine Fx) will cover all the MASH motion graphics toolset nodes.
Shinde discusses the Flight Node in MASH in Maya and how to render with Arnold Renderer.
This other tutorial by 3D Artist Maximilian Schönherr shows how to combine MASH and bullet dynamics to create animation. Visit that tutorial here.