It is very clear which force powers are used by Light Jedi and which are used by Dark Jedi, Shadow Jedi have a unique force inventory at their disposal. A Shadow Adept can use both Light and Dark Adept Force powers, however they have their own special techniques separate from both Light and Dark.
The techniques are variations of standard Light and Dark powers however they differ in that they are not as polarised as both Light and Dark. Light adepts most potent force magic is arguably the Force Blind, in which opponents are blinded by light. Dark adepts have Force Lightning which is used as a weapon to burn and rupture blood vessels and cells throughout the body. A shadow adept has a combination of these powers at their disposal; the ability to 'darken' their opponents vision whilst sending out tendrils of darkness which taps opponents energy. This is perhaps the most potent of a Shadow adepts powers, the ability to reduce opponents vision whilst taping their energy can tip the balance of any light fight.
However Shadow Jedi rarely engage in combat, as stated before Shadow Jedi are a secretive sect of Jedi. Shadow adepts have been around for centuries, some say they evolved before Light and Dark, their powers are both similar and unique in comparison to both Dark and Light Jedi.