Rainbow: Vivid Variegation
Gold: Gilded Glow
Team Color: Polychromatic Passion

Note: This makes use of a workshop-contributed resource "materials/effects/workshop/god_ray_trail.vmt". I was making my own version of the material for this effect, but realized it already existed. Nice.
All other custom resources were self-drawn.

This was partially made as a simple proof-of-concept: all four particle systems share the same "children". Through manipulating the parent system's control points, these particle systems can achieve any color range desired.
For reference, other Unusual effects that have color variants (i.e. Kill-a-Watt and Terror-Watt) clone all associated particle systems and manually recolor them.