Well actually, lightning apparently helps grass and plants (indirectly of course otherwise it would cause a fire) which could explain grass's resistance to it. For the sake of giving it another advantage just to make it on more equal terms with fire and water, sure I guess grass can >electric. It is a lot more far fetched than it resisting electric though. What can grass, or even the tallest tree do against a bolt of lightning?
Drain the Electric poke of its electricity and redirect it into the ground maybe?... :S