Grass
Though it looks pointless now with the amount of support Electric has. I'll be very interested to see what people have in mind for an electric type since defensively it's rather poor regardless of what it's coupled with other then Steel.
Offensively it is of course is rather strong, though still does suffers an unfortunate ground immunity, not to mention Volt Absorb and Motor Drive.
Disappointed because I was really hoping for an assertive Grass/Steel type, lol. I feel it would have been a fairly versatile typing, especially granted a decent move pool.