As in your team thread, Avalugg is still terrible in Ubers because of its Stealth Rock weakness. Excadrill sees better use:
-Earthquake
-Rapid Spin
-Swords Dance
-Rock Slide/Shadow Claw
Nature: Adamant
EVs: 176 HP/60 Atk/252 SDef/20 Spe
Item: Leftovers
Ability: Mold Breaker
Note that Shaymin and Dialga are unavailable until Poke Bank is released.
Yveltal is versatile, so it can run a multitude of sets, but the mixed set should make do with Life Orb, since Dark Gem isn't available at the moment.
Stealth Rock isn't available for Blissey yet until Poke Bank:
-Aromatherapy
-Seismic Toss/Flamethrower
-Softboiled
-Toxic
Nature: Bold
EVs: 4 HP/252 Def/252 SDef
Item: Leftovers
Ability: Natural Cure
Until Poke Bank is released, you need to make do with Xerneas and Mewtwo in place of Dialga and Shaymin:
Xerneas:
-Geomancy
-Moonblast
-Substitute
-Hidden Power (Fire)/Focus Blast
Nature: Modest
EVs: 192 HP/252 SAtk/64 Spe
Item: Power Herb
or
-Moonblast
-Close Combat
-Hidden Power (Fire)
-Thunderbolt/Thunder/Calm Mind
Nature: Hasty/Naive
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb
or
-Moonblast
-Close Combat
-Megahorn
-Thunderbolt/Thunder
Nature: Hasty/Naive
EVs: 76 Atk/180 SAtk/252 Spe
Item: Choice Scarf
Mewtwo:
-Psystrike
-Ice Beam
-Aura Sphere/Fire Blast
-Fire Blast/Calm Mind
Nature: Timid
EVs: 4 Def/252 SAtk/252 Spe
Item: Life Orb/Mewtwonite Y
or
-Calm Mind
-Psystrike
-Flamethrower/Aura Sphere/Ice Beam
Nature: Timid
EVs: 252 HP/4 Def/252 Spe
Item: Leftovers/Mewtwonite Y
or
-Taunt
-Recover
-Will-o-Wisp/Toxic
-Psystrike/Light Screen/Substitute
Nature: Timid
EVs: 252 HP/72 SDef/184 Spe
Item: Leftovers
or
-Psystrike
-Ice Beam
-Aura SphereFlamethrower/Fire Blast
-Fire Blast/Flamethrower
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Scarf