Okay so by this title you may be saying sartorius im sorry but the dark ball is to over powered well that's where you are wrong while yes this pokeball is based off of the original dark ball this dark ball is much much more weaker than the original dark ball how you ask well i will show you.
Original dark Ball
Name: Dark Ball
Purpose: Pokémon captured with a Dark Ball will become evil and their power will increase to the highest level. The Pokémon loses its freedom and will obey all commands of its master. able to bring pokemon all ready owned by other people under your control. The control of a Dark Ball can be fought and even broken if the Pokémon has enough willpower. Should this happen, the Dark Ball that captured it will be destroyed.
Looks: Item Type:pokeball
Anything else: not really but if your intrested on finding out more here you go: http://bulbapedia.bulbagarden.net/wiki/Dark_Ball
(Now here is my suggestion for the new and not overe powered dark ball)
Name: Dark Ball
Purpose: Pokémon captured with a Dark Ball will become a dark version of that pokemon but there stats stay the same as normal versions of there type as the pokemon captured by the dark ball levels up. The pokemon is able to learn dark moves by tm if the pokemon cant learn dark moves by leveling up.
Looks: Item Type:pokeball
Anything else: none