Quoted By:
+2 252 SpA Life Orb Serperior Hidden Power Fire vs. 252 HP / 168 SpD Ferrothorn: 359-426 (101.9 - 121%)
+2 252 SpA Life Orb Serperior Hidden Power Fire vs. 252 HP / 4 SpD Skarmory: 315-372 (94.3 - 111.3%)
+2 252 SpA Life Orb Serperior Leaf Storm vs. 252 HP / 252+ SpD Empoleon: 274-324 (73.6 - 87%)
+2 252 SpA Life Orb Serperior Dragon Pulse vs. 0 HP / 0 SpD Mega Charizard X: 382-452 (128.6 - 152.1%)
+2 252 SpA Life Orb Serperior Leaf Storm vs. 252 HP / 0 SpD Mega Altaria: 183-217 (51.6 - 61.2%)
+6 252 SpA Life Orb Serperior Leaf Storm vs. 4 HP / 252 SpD Eviolite Chansey: 390-460 (60.7 - 71.6%)
+2 252 SpA Life Orb Serperior Dragon Pulse vs. 4 HP / 0 SpD Latios: 309-364 (102.3 - 120.5%)
+2 252 SpA Life Orb Serperior Hidden Power Fire vs. 0 HP / 0 SpD Mega Metagross: 221-260 (73.4 - 86.3%)
252 SpA Life Orb Serperior Leaf Storm vs. 0 HP / 0 SpD Metagross: 88-105 (29.2 - 34.8%)
+2 252 SpA Life Orb Serperior Hidden Power Fire vs. 248 HP / 8 SpD Mega Scizor: 468-556 (136.4 - 162%)
Walled by Heatran, of course, but I think that's a fair trade-off for beating almost every other Steel-type in OU.
Serp has base 113 Speed and 75 / 95 / 95 bulk, too.