ahem... how's crunch or pursuit terrible in anyway? They're both excellent moves if you put it on the right stats. Don't sue the moves... sue those crappy Pokemon who learns it (only good crunch/pursuiter: Tyranitar, Houndoom, Salamence, Flygon, Charizard, Raikou)
*note: just because those Pokemon can use crunch well, that doesn't mean they have to use crunch/pursuit, because they just may have even better moves!
Bug types need no boost. Bug Pokemon generally does need it. However bug types are still a lot stronger than grass. Out of the bugs, there's still heracross leading the crowd, with pinsir, scizor, ninjask, Armaldo (more recognized by rock blast rather than being a bug though) and Forretress following behind. Silver wind and megahorn are both very powerful bug attacks, along with HP Bug for nice STAB along with fast speed and good attack power. Type advantage over dark and psychic are quite nice, with a strong point towards Ludicolo as a bonus. It's just the stats of the Pokemon that needs some fixing.
So what's good in grass?
-Breloom, sceptile, Ludicolo, Celebi, Exeggutor, and occassional Venusaur
Though grass types have a higher amount in terms of usable, grass types have major weaknesses to many types (ice, poison, fire, flying for exampel) and there isn't really much good grass moves... notice that all of those listed Pokemon don't really rely on grass damage moves except Exeggutor solarbeam and Sceptile with Leaf blade. Their stats suck just as much, and their type advantage is even worst than bug...