To clarify that with a pertinent quote from the Common Wording Errors Compilation:For Oricoro's ability, it's energy cards, not energy. Hopefully that helps! http://www.pokebeach.com/forums/threads/the-common-wording-errors-compilation.128701/
Energy is Energy when attached, it’s an Energy card when not. This means you can’t search your deck for Energy. [Reference: Palkia-EX, Lugia-EX, Fisherman, Aromatisse XY, Shuppet ROS]
So Dancer should say "Energy card" in both instances, but Revelation Dance is "Energy".