Mega Sharpedo-EX, the new(ish) promo card, has huge potential with a low retreat cost and damage to the opponent's bench. The strategy of this deck combines this and Yveltal BREAK, which can also be a great help in dishing out extra damage.
Pokémon: 15
3x M Sharpedo-EX
3x Sharpedo-EX
3x Yveltal BREAK
3x Yveltal (STS)
2x Tapu Lele-GX
1x Shaymin-EX
Items: 18
4x Max Elixir
1x Mega Turbo
3x VS Seeker
4x Ultra Ball
3x Sharpedo Spirit Link
2x Choice Band
1x Field Blower
Supporters: 11
4x Professor Sycamore
2x N
1x Ace Trainer
1x Hex Maniac
1x Brock's Grit
2x Guzma
Stadiums: 5
3x Team Aqua's Secret Base
2x Altar of the Moone
Energy:
8x Darkness Energy
3x Dangerous Energy
Pokémon: 15
3x M Sharpedo-EX
3x Sharpedo-EX
3x Yveltal BREAK
3x Yveltal (STS)
2x Tapu Lele-GX
1x Shaymin-EX
Items: 18
4x Max Elixir
1x Mega Turbo
3x VS Seeker
4x Ultra Ball
3x Sharpedo Spirit Link
2x Choice Band
1x Field Blower
Supporters: 11
4x Professor Sycamore
2x N
1x Ace Trainer
1x Hex Maniac
1x Brock's Grit
2x Guzma
Stadiums: 5
3x Team Aqua's Secret Base
2x Altar of the Moone
Energy:
8x Darkness Energy
3x Dangerous Energy