Riku's Dark Jutsu's

Chakra nature: Fire, Lightning, Darkness

Dark Creation: Riku can use any of his dark chakra and if wanted an element to make a weapon like a sword or a kunai.

Shadow Control: Riku can control shadows around him to make things like a shadow dummy or anything

Dark Judgement: When Riku gets hurt enough he can use this to get filled with a great amount of dark power but he loses control and goes berserk when he does so he always needs somebody to calm him down fast when he uses it

Dark Shot: Riku shoots out a medium sized shot of darkness from his palm.

Dark Wave: Kyo uses up some of his dark energy and chakra to shoot out a Giant Wave of darkness from both of his hands, but doing that causes him to become tired for a little while as he gains back his energy

Ok. If you have fire and lighting chakra elements, Y are you using the darkness element. That's what I'm not understanding. Fix this please.

The darkness is infused with it along with everything else he has, and he doesnt like to use Fire or lightning much he just likes to use pure darkness

Ok. Add the darkness element in with your chakra natures and I can approve you.

Okay will do