I don't know about VGC, but on Pokémon Showdown, Rillaboom, Ferrothorn, Kartana are OverUsed in Gen 8 Sw/Sh. Some will remember Roserade being a dangerous threat in Gen 4 OverUsed. Serperior, Tangrowth, Tapu Bulu... also had their moment of glory in OverUsed.
But overall, the Grass type is kinda weak, too many weaknesses to very common coverage types (Fire, Flying, Ice + weakness to U-Turn), the Grass-type is resisted by too many types. It's hard to justify using a Grass-type Pokémon in your OU team unless it hits very hard (Kartana, Rillaboom, Roserade in Gen 4, Serperior, Tapu Bulu in Gen 7) or has usable defensive stats (Tangrowth, Ferrothorn) 🤔
So I agree, it *can* be good, but it generally isn't...
Humanity is now completely dependent on computers.