No. GrassSludge (as I call it) is the new BoltBeam. Energy Ball/Giga Drain with Sludge Bomb/Sludge Wave makes an unresisted combination, except for Sawsbuck. Bolt-Beam is resisted by pure Ground-types, maybe more, IDK.
It's also resisted by any Flying-type as long as they don't carry a secondary type to make them weak to BoltBeam










