I'm actually considering to do a pseudo-Nuzlocke challenge for Pokemon Colosseum. It's a pseudo challenge due to the nature of the game, normal Nuzlocke rules would be hard to do.
  1. When a pokemon faints, shadow or purified, it is dead. (aka either released or put into a box never to be used again.)
  2. You cannot attempt to capture the shadow pokemon during rematches. This means the only time you are allowed to snag a Shadow Pokemon is on the first encounter with the trainer.
  3. All purified pokemon must have a nickname.
  4. (Optional, but highly encouraged:) Purify ALL the shadow pokemon!!
  5. (Optional:) Whenever a Shadow Pokemon enters Hyper/Reverse Mode, you MUST spend your next turn calling it out of it.
  6. XD Only: You can only snag one Shadow Pokemon per trainer.
  7. XD Only: You can catch only one pokemon from each Poke Spot.