

Latias @ Latiasite
Ability: Levitate
EVs: 248 HP / 68 Def / 192 Spe
Timid Nature
- Whirlpool
- Reflect Type
- Hidden Power [Fire]
- Roost
Serperior @ Leftovers
Ability: Contrary
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Leaf Storm
- Dragon Pulse
- Taunt
- Knock Off
Ability: Levitate
EVs: 248 HP / 68 Def / 192 Spe
Timid Nature
- Whirlpool
- Reflect Type
- Hidden Power [Fire]
- Roost
Serperior @ Leftovers
Ability: Contrary
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Leaf Storm
- Dragon Pulse
- Taunt
- Knock Off
Latias lures and kills Steels - Ferrothorn, Heatran, Scizor, and sometimes even Mega-Metagross - which gives Serperior a chance to sweep. This particular Serperior set is built to mess with fatter teams really hard (since Latias is pretty useless there), but the point is that Latias frees up the third slot (which is typically reserved for HP Fire or HP Ground), so you can pick a two-move combination that you like out of Taunt, Leech Seed, Substitute, Glare, Knock Off, and Giga Drain. Having access to two of these moves instead of one can seriously help in breaking down fat teams. Needs support in the form of Flying checks/counters (Torn-T, Talonflame, Pinsir etc). Thunder Wave is also an option on Latias over RType/HP Fire, but you're losing the ability to beat either Bisharp/Tyranitar or Ferro/Scizor.