A combination of the Runaway Post-it Notes and the 3D Game Sprites projects.
I used two different but similar game sprites, Mario and Luigi from the original Mario Bros. game. They only differ in color palette. The color attribute is blended down the Y-axis to get a nice gradient as the paper blows away.
With so many stacks of particles, I needed each of the stacks' particles to be grouped from top to bottom at a random rate. The first step was to set an attribute that specifies the "stack number" in SOPs. I set the Alpha ($CA) point attribute equal to the point number ($PT) of the template. That stack number ($CA) is kept after the Copy SOP so that the particles can use it.
Next, in the particle network, I created a random step curve in CHOPs which goes up by increments of 1 at a random rate. I created as many curves as I needed. The names of these curves will correspond to the stack number of the particle.
Finally, by using an expression, I got the particles to group from top to bottom. The modulo operator is very useful. Particles within this group will be effected by the wind and other forces.