I agree wholeheartedly with DarkBlazer. The SD set is great, but the utility that Low Sweep provides is amazing. You're able to 2hko Tornadus-T after rocks with Low Sweep, who should be a great check to breloom. A lot of tornadus-T are beginning to run Sleep Talk to better deal with spore, but that's not going to help when it's being 2hko'd by low sweep.
With Spore you can essentially take out a pokemon from the game. Often times, against offensive teams they will just let their sleeping pokemon stay asleep, seeing as how it's going to be difficult for breloom to use spore twice.
The SD set is great against defensive oriented teams, but I don't believe the extra turn to set up that SD is really necessary.
the Bulk Up set used to be very good with BW1 Voltturn running around. But with Genesect and Tornadus-T's popularity, it's just not as effective as it used to be.
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