Originally Posted by Fat bugmaniacbob
The foe's Makuhita used Ice Punch!
Cofagrigus lost 43% of its health!
The foe's Makuhita lost some of its HP!
Cofagrigus is fast asleep.
Cofagrigus used Sleep Talk!
Cofagrigus used Hidden Power!
It's not very effective... The foe's Makuhita lost 12% of its health!
This was with Hidden Power Fighting, which should have been neutral vs. the pure Fighting-type Makuhita. If it makes any difference, Makuhita's ability had been changed to Mummy beforehand. I'm pretty sure there's a bug here.
Replay for reference: http://pokemonshowdown.com/replay/randombattle2503996
(see turns 19 and 21)
There's a bug with moves that call Hidden Power indirectly that causes it to become Hidden Power Dark in Random Battles / Challenge Cup, because it treats your pokemon with its full 31 IVs in everything (which results in the Dark typing) rather than calling the Hidden Power move of the correct type.