Sylveon/Pixelate
Bold
252 Def, 252 HP, 4 SpD
Leftovers
Protect
Moon Blast
Calm Mind
Skill Swap
Desription: Star Lead of the team. Protect to burn out Fake Out, because he is bait when Chandelure/Trevenant comes with it. Skill Swap surprises an unknowing Mega Kangaskhan, Prankster user to name a few. It removes Gale Wings making Talonflame frail under Trick Room. But even if there's no useful ability to grab from the opponent, it gives perfect synergy to Snorlax, giving Sylveon Thick Fat, further boosting its nice SpDef, while transferring Pixelate to Snorlax - a good physical attacking dark/dragon/fighting killer. Calm Mind is useful under Trick Room/Prankster. Finally, Moonblast is its primary STAB move.
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Chandelure/Flash Fire
Modest
252 HP, 252 SpA, 4 SpD
Focus Sash
Protect
Fire Blast/ Heat Wave (Post Pokebank)
Shadow Ball
Trick Room
Description: Main use is to set up Trick Room. But after that, it should still be a good attacker. Shadow Ball to beat Attack mode Aegislash. Fire Blast to beat steel/grass types, though Heat Wave is a better option once Pokebank comes out. Protect rounds off its move set.
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Snorlax/Thick Fat
Brave
252 HP, 252 Atk, 4 SpD
Assault Vest
Body Slam
Earthquake
Crunch
Rock Slide
Description: Makes up half over the Sylveon-Snorlax duo. Terrible speed makes him good under Trick Room. SpDef is already good without Thick Fat, so he can have Pixelate. Body Slam Fairy would be perfect for Dragon/Fighting/Dark Types. Earthquake for rock types. Crunch for Ghosts. Rock Slide for Flying types.
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Ampharos/Static
Modest
252 SpA, 200 HP, 56 Def
Ampharosite
Protect
Dragon Pulse
Thunder Bolt
Focus Blast
Description: I had a hard time filling out the mega slot but figured that this mega evolution probably gives the best synergy over the rest of the megas available. He also works well under trick room and gives balance to the mostly specially defensive team with good its Defense. Focus Blast would take care of steel/dark/normal. Thunder Bolt and Dragon Pulse are its reliable STAB attacks.
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Trevenant/Harvest
Impish
252 HP, 252 Def, 4 SpD
Sitrus Berry
Protect
Will O Wisp
Wood Hammer
Trick Room
Description: Alternate Trick Room setter, used for Rain/Sandstorm teams. Wood Hammer is its main STAB. Will o wisp to weaken Physical Attackers. Harvest Sitrus Berry also ensures its longevity.
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Gyarados/Intimidate
Impish
252 HP, 200 Def, 56 Spe
Gyaradosite
Protect
Dragon Dance
Waterfall
Ice Fang
Description: Alternate Mega. Dragon Dance increases its speed and attack once trick room ends. Waterfall and Ice Fang are my choice attacks.
Bold
252 Def, 252 HP, 4 SpD
Leftovers
Protect
Moon Blast
Calm Mind
Skill Swap
Desription: Star Lead of the team. Protect to burn out Fake Out, because he is bait when Chandelure/Trevenant comes with it. Skill Swap surprises an unknowing Mega Kangaskhan, Prankster user to name a few. It removes Gale Wings making Talonflame frail under Trick Room. But even if there's no useful ability to grab from the opponent, it gives perfect synergy to Snorlax, giving Sylveon Thick Fat, further boosting its nice SpDef, while transferring Pixelate to Snorlax - a good physical attacking dark/dragon/fighting killer. Calm Mind is useful under Trick Room/Prankster. Finally, Moonblast is its primary STAB move.
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Chandelure/Flash Fire
Modest
252 HP, 252 SpA, 4 SpD
Focus Sash
Protect
Fire Blast/ Heat Wave (Post Pokebank)
Shadow Ball
Trick Room
Description: Main use is to set up Trick Room. But after that, it should still be a good attacker. Shadow Ball to beat Attack mode Aegislash. Fire Blast to beat steel/grass types, though Heat Wave is a better option once Pokebank comes out. Protect rounds off its move set.
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Snorlax/Thick Fat
Brave
252 HP, 252 Atk, 4 SpD
Assault Vest
Body Slam
Earthquake
Crunch
Rock Slide
Description: Makes up half over the Sylveon-Snorlax duo. Terrible speed makes him good under Trick Room. SpDef is already good without Thick Fat, so he can have Pixelate. Body Slam Fairy would be perfect for Dragon/Fighting/Dark Types. Earthquake for rock types. Crunch for Ghosts. Rock Slide for Flying types.
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Ampharos/Static
Modest
252 SpA, 200 HP, 56 Def
Ampharosite
Protect
Dragon Pulse
Thunder Bolt
Focus Blast
Description: I had a hard time filling out the mega slot but figured that this mega evolution probably gives the best synergy over the rest of the megas available. He also works well under trick room and gives balance to the mostly specially defensive team with good its Defense. Focus Blast would take care of steel/dark/normal. Thunder Bolt and Dragon Pulse are its reliable STAB attacks.
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Trevenant/Harvest
Impish
252 HP, 252 Def, 4 SpD
Sitrus Berry
Protect
Will O Wisp
Wood Hammer
Trick Room
Description: Alternate Trick Room setter, used for Rain/Sandstorm teams. Wood Hammer is its main STAB. Will o wisp to weaken Physical Attackers. Harvest Sitrus Berry also ensures its longevity.
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Gyarados/Intimidate
Impish
252 HP, 200 Def, 56 Spe
Gyaradosite
Protect
Dragon Dance
Waterfall
Ice Fang
Description: Alternate Mega. Dragon Dance increases its speed and attack once trick room ends. Waterfall and Ice Fang are my choice attacks.