Scyther

Despite a crippling 4x weakness to Stealth Rock, Scyther is an extremely dangerous and often underestimated UU sweeper. Its great dual STABs provide excellent neutral coverage, and also hit many common defensive Pokemon for super effective damage (including Hitmontop, Uxie, Venusaur, and Slowbro). In addition, its high Speed and welcome resistances to Fighting and Grass means that it can check and revenge kill many common offensive Pokemon. However, Stealth Rock is hostile to Scyther, shaving off a substantial 50% of its HP; dedicated Rapid Spin support is nearly essential to ensuring success with Scyther. Despite this admittedly large flaw, mustering up the necessary support is definitely worth it when you consider Scyther's destructive potential.