Those are referring to the Shadow moves known by shadow Pokemon in Pokemon Colosseum and Pokemon XD, both for the Gamecube.
Pokemon's hearts are closed by these evil orginizations, and with that, they become posessed with an ominous power that controls them.
This means that the pokemon learn Special moves that take advantage of this strange power. These Shadow moves are Super-effective to every Pokemon, have no PP capacity, and can put your Pokemon into a strange status ailment called "Hyper Mode" ("Reverse Mode" for Pokemon XD.)
This Ailment doubles the Critical-Hit Rate of Shadow Moves, but you take recoil damage at the end of every turn.
You can also heal these Shadow Pokemon to restore them to their original form, by means of battling with them, walking around, etc. (Think of it as the Happiness factor in normal Pokemon games.)
Anyway, that's my HUGE article on Shadow Pokemon. :P