>>15135378Grass actually seems to have decent synergy with fairy. It's immune to the powders/spores, and gets like 4 extra resistances, doesn't get the bug weakness, the poison weakness that would kill you anyway just overlaps, so now you're basically a Grass type with better neutral coverage, a weakness to steel, a few more resistances, and an immunity to dragon.
Though now I realize that's basically me saying that adding Fairy to Grass is a good choice, going the opposite way of adding grass to fairy probably does make it worse now that I think about it