Grass has immunity to Spore(s), Leech Seed and a resistance to Earthquake, Water too. That's all pretty dandy defensively.
Despite its multiple weaknesses, Bug and Poison aren't that common enough for a Grass type not to thrive against such odds.
Not only that, when paired with another type like Poison or Steel which have a Toxic immunity and some proper bulk, you've got menaces like Ferrothorn, Venusaur, or Amoongus running about.
Or even alone you have the likes of Tangrowth and Serperior who were mentioned already here.
I honestly used to think Grass was one of the worst types to have, but I've given it some thought, that's definitely wrong these days.
I still think Rock, Bug, and Ice are the absolute worst though lol
