EVs and natures would be appreciated.
Note that you can only Mega Evolve once per battle, so I'd dedicate the Mega slot to one Pokemon only, so as not to waste an item slot when a Pokemon does Mega Evolve.
Lack of STAB hurts on Tyranitar. While it has a wide move pool, some options are more practical on it than others:
-Crunch
-Stone Edge/Rock Slide
-Pursuit
-Stealth Rock/Fire Blast
Nature: Careful/Sassy
EVs: 252 HP/4 Atk/252 SDef
Item: Leftovers/Assault Vest
Ability: Sand Stream
or
-Crunch
-Pursuit
-Earthquake
-Stone Edge/Ice Beam
Nature: Jolly/Hasty
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Scarf
Ability: Sand Stream
or
-Crunch
-Stone Edge
-Pursuit
-Earthquake/Ice Fang
Nature: Adamant
EVs: 180 HP/252 Atk/76 Spe
Item: Choice Band
Ability: Sand Stream
Moonblast and Dazzling Gleam are redundant on Sylveon. The former is the superior option, while the latter may see use in doubles, due to being a spread move:
-Wish
-Protect
-Moonblast
-Shadow Ball/Hidden Power (Fire)
Nature: Bold
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
or
-Calm Mind
-Moonblast
-Shadow Ball
-Hidden Power (Fire)/Psyshock
Nature: Modest
EVs: 252 HP/252 SAtk/4 Spe
Item: Leftovers
Blast Burn is not worth using ever because it leaves Blaziken a sitting duck the next turn:
-Flare Blitz
-High Jump Kick
-Protect
-Swords Dance/Baton Pass
Nature: Adamant/Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Blazikenite/Life Orb
Ability: Speed Boost
Blastoise is only good in its Mega form. The same applies to Venusaur outside of Sun. For the sake of examples, Greninja and Chesnaught are the superior options without competing for a Mega slot:
Greninja:
-Hydro Pump/Surf
-Dark Pulse
-Ice Beam
-U-turn/Hidden Power (Fire)
Nature: Hasty/Timid
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb
Ability: Protean
or
-Spikes
-Hydro Pump/Surf
-Dark Pulse/Ice Beam
-Hidden Power (Fire)
Nature: Timid
EVs: 4 Def/252 SAtk/252 Spe
Item: Life Orb/Focus Sash
Chesnaught:
-Spikes
-Synthesis
-Hammer Arm
-Roar/Stone Edge/Seed Bomb/Leech Seed
Nature: Impish
EVs: 252 HP/252 Def/4 Spe
Item: Leftovers
Ability: Bulletproof
or
-Bulk Up
-Seed Bomb/Wood Hammer
-Hammer Arm
-Stone Edge
Nature: Adamant
EVs: 252 HP/252 Atk/4 Spe
Item: Leftovers
Ability: Bulletproof
(though this is outclassed, I suggested it for the sake of convenience)
Lucario can function just fine without its Mega Stone, though it should stick to a physical set:
-Swords Dance
-Close Combat
-Extreme Speed
-Crunch/Shadow Claw/Earthquake
Nature: Adamant/Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb
