I couldn't believe no one typed a ball like my "the ring" one.
Berserk Ball: Pokemon goes crazy and kills everything (except you) that comes in its path!
Flesh-Eater Ball #1: Caught Pokemon has sudden cravings for meat... like me...
Flesh-Eater Ball #2: When thrown, it tries to eat the Pokemon.
Skull Ball: Pokemon is haunted by the Grim Reaper
(Side effects to using this pokeball may include missing limbs, unlogical phobias, hair loss, and possibly death!!)