>>33406394Grass is great defensively, since it resists Ground and Electric. Remember how annoying those Rotom/Landorus cores used to be? A good Grass type walls them both. And being immune to Powder type moves is a huge plus too. the thing is, grass fans tend to want their pokemon to be unstoppable warriors, sine that's how they are with your starter in-game. Unfortunately, it's really more about godly support and defenses, offensively, it's not that great. Just a case of people liking things for what they want them to be rather than liking stuff for what it is. Plenty of strong defensive Grass types all over OU and UU, like Mega Venusaur, Amoongus, the aforementioned Tangrowth, and Ferrothorn. And of course, there are a couple offensive grass types that excel in spite of their typing due to having amazing abilities, namely Tapu Bulu, Serperior, Breloom, and Kartana. Mega Sceptile is what happens when a Grass type tries its absolute hardest to be a warrior, and it's okay but imagine if it were, say, a Fire type. Those Overheats would be way more terrifying than its Leaf storms. Mega Venusuar is what happens when a grass type embraces its role as a bulky supporter, and it excels at being an annoying pain in the ass to deal with, spreading around Leech Seeds, Poisoning things, and tanking hits that would make lesser pokemon squirm. Now imagine for a second in Mega Venusaur were Fire/Poison instead of Grass/Poison. It wouldn't be able to switch in as much since its weak to Stealth Rock now, can't tank even a weak Ground type move, and gets shit on hard by Stone Edge+Earthquake, a really common offensive combination. Suddenly all that bulk isn't helping it and you wish it were faster like Sceptile.
Grass is fine, it has it flaws, but then again, everything but Steel has major flaws. Grass is just good at doing stuff people don't find very exciting.