>>54358003I mean, that's also a thing in single-player tho.
Grass-types gets access to all the powder moves and leech seed and you even have all the Mushroom mons that are exclusively grass and have access to Spore. Grass-types also have all the draining moves and things like Morning Sun and Synthesis.
Fire is about nuking shit, Water is all-arounders, Grass is for weirdos that want to be more technical in their single-player campaign. All of these are equally viable, except most people will choose quicker options, especially that battle system in Pokemon already is sluggish in comparison to other jrpgs.