Ferroseed is and always will be really good as a hazard setter.
Murkrow isn't broken, it just needs preparation for like everything else in the meta-game. LO 4 attacks is indeed very dangerous but as Ray said, it burns itself out quickly. It does, however have very few reliable checks due to the great coverage it gives and HP grass beating things like hippo and tirtouga. Porygon is still a pretty solid answer, but I think aron has to be the best I've used (and it can still do other stuff too which is cool).
I've actually been using natu a lot myself (as a TR setter, no less!) and it works very well. Not only does it completely shut down the omnipresent hippopotas, it's really useful instead of having to pack staryu all the time as it beats nearly all hazard setters as sir said bar dwebble (who needs more usage IMO).
Scraggy is low because he can't get round mienfoo and drilburr with one set, and both of which are on high usage. And also, thankfully, people are discovering more DDers like Axew or dratini.
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