Board Thread:Theories and Rumors/@comment-36592086-20180824010531/@comment-30499831-20180824174505

"According to his original Character Card, Lloyd's dominant element is Lightning, explaining why he was shown using the Nunchucks of Lightning in Zane's dream in Never Trust a Snake and why the Golden Weapons made green lightning when they revealed he was the Green Ninja. It also parallels Lord Garmadon, his father, who's dominant element is Dark Lightning."

Well.. keep in mind, something like that isn't exactly canon. Garmadon's power isn't even called "Dark Lightning", people just called it that because it looks like purple lightning Spinjitzu. Garmadon's element in the card game is "All".