Yveltal @ Heavy-Duty Boots / Choice Scarf
Ability: Dark Aura  
EVs: 252 HP / 4 Def / 252 SpD or 248 HP / 8 Def / 68 SpD / 184 Spe
Careful / Jolly Nature  
- Foul Play / Knock Off
- U-turn / Snarl
- Defog / Taunt
- Roost

Yveltal @ Life Orb
Ability: Dark Aura
EVs: 4 Atk / 252 SpA / 252 Spe
Mild Nature
- Dark Pulse
- Oblivion Wing
- Sucker Punch
- Taunt / Roost / Heat Wave

Yveltal @ Life Orb  
Ability: Dark Aura  
EVs: 188 Atk / 68 SpD / 252 Spe  
Adamant Nature  
- Knock Off  
- Dual Wingbeat  
- Sucker Punch  
- Roost / Hone Claws