There is no Meta but i'll bite anyway.
Groudon is clearly not the best grass attacker. Grass' only usefulness is for beating water and water is SE vs Groudon. Combined with groudon not having a grass quick move, it won't outperform eggy.
Grass' strength against Ground and Rock are pointless, water beats them aswell and everyone's got water types. I don't play anymore but this stuff is still really obvious.
gamepress are wrong on this one. You can thank me later ;)