Should be in TCG Questions, so I moved it.
Anyway, Holon's Magneton/Electrode/DRE all provide every single type of energy. When an attack asks to discard all Lightning energy (as an example) then you would HAVE to discard since they provide lightning energy.
If an attack says Discard 2 energy or similar then you are not forced to discard them, but they do count as 2 energy.