Ok, there are some things I see wrong with the team but Ima clean it right up, so don't you worry. I will be replacing 4 of your pokemon, those being Breloom, Forretress, Ferrothorn, and Espeon.
Hydreigon - He can run a decent Choice Specs set but I find that he runs a better Choice Scarf set. Your EVs are messed up, I think you mean SAtk instead of Atk. As previsouly stated, change his item to a Choice Scarf, change Flamethrower to Fire Blast, change Dragon Pulse to Draco Meteor, and change Focus Blast to U-turn. Also, run a Hasty Nature over Modest and change 4 Def to 4 Atk.
Changes
- Choice Scarf > Choice Specs
- 4 Atk / 252 SAtk / 252 Spd > 252 Atk / 4 Def / 252 Spe
- Hasty Nature > Timid Nature
- Fire Blast > Flamethrower
- Draco Meteor > Dragon Pulse
- U-turn > Focus Blast
Ninetales - I'm not completely on board here, but I have a nice defensive Ninetales that I have used with fairly positive results. it should work for you very nicely.
Ninetales @ Leftovers
Trait: Drought
EVs: 108 HP / 4 Def / 144 SAtk / 252 Spd
Timid Nature
- Solarbeam
- Flamethrower
- Sunny Day
- Will-O-Wisp
Solarbeam is for coverage, Flamethrower is STAB and hits decently hard thanks to Drought. Sunny Day is one of the most important moves on the set, as it allows Ninetales to beat the infamous Politoed. Politoed is the #1 switch-in to Ninetales, so when you see a Poli switch coming (they aren't hard to predict), you just use Sunny Day. SO Poli comes in and sets up Rain, then BAM, the sun is out again, and Poli can't touch Ninetales in the Sun. Last but not at all least Will-O-Wisp is for crippling physical attackers.
Changes
- Leftovers > Focus Sash
- 108 HP / 4 Def / 144 SAtk / 252 Spd > 252 HP, 252 SpDef, 4 Spe
- Timid Nature > Calm Nature
- Solarbeam > Thunder Wave
- Will-O-Wisp > Confuse Ray
- Sunny Day > Substitute
Forretress - I am afraid Forretress is going to be replaced, he will end up being death fodder what with that huge Fire weakness. And replacing Forry, we have (drum roll) .......
Cloyster!
Cloyster - Cloyster is typcally used as a Shell Smash sweeper but it also runs a nice utiility set, and Smogon has a noce on that I will be recommending to you.
Cloyster @ Leftovers
Trait: Skill Link
EVs: 248 HP / 84 Atk / 176 Def
Impish Nature
- Icicle Spear
- Rapid Spin
- Spikes
- Ice Shard
Icicle Spear is STAB and hits multiple times, breaking substitutes and such. Rapid Spin spins away Stealth Rock, which commonly spells doom for sun teams. Spikes is for setting up your own hazards and Ice Shard is STAB and gets priority.
Breloom - I am going to replace Breloom for a different grass type, but a grass type that is great at abusing sun. Your Breloom replacement is.....
Venusaur!
Venusaur - I am going to give you a mixed Growth set, which is great at abusing sun with Chlorophyll.
Venusaur @ Black Sludge
Trait: Chlorophyll
EVs: 252 Atk / 4 SAtk / 252 Spd
Lonely Nature
- Growth
- Power Whip/Seed Bomb
- Earthquake
- HiddenPower [Rock]
Growth boosts your offensive stats, Power Whip/Seed Bomb is STAB, if you want brute force use Power Whip, if you want reliability go with Seed Bomb. Eartthquake is coverage, as is HP [Rock].
Changes
- Venusaur > Breloom
Espeon - Espeon kind of enhances the teams bug weakness, and that is a problem, so I am going to suggest a different Magic Bouncer.
Xatu!
Xatu - Xatu is a very unique pokemon, and although he has a weakness to Rock that the team doesn't need, he resists fighting, is immune to gorund, and is not weak to bug, all the while retaining Magic Bounce, making for a great support pokemon for the team.
Xatu @ Leftovers
Trait: Magic Bounce
EVs: 248 HP / 204 Def / 56 Spe
Bold Nature
- Thunder Wave
- U-turn
- Roost
- Heat Wave
Thunder Wave cripples opponents usually lets you go first, and U-turn lets you get away. Roost is for recovery and Heat Wave is boosted by the sun and takes things like Scizor and Ferrothorn.
Changes
- Xatu > Espeon
Ferrothron - Ferrothorn I am also going to replace (mostly due to his Fighting weakness), with...
Jellicent!
Jelllicent -Jellicent benefits the team by tanking Ice, Fighting, and Water type moves, and while he shares Ghost and Dark type weaknesses with Xatu, Jellicent should fit your team very well, and despite his water typing, he is still a menace even in the sun.
Jellicent @ Leftovers
Trait: Water Absorb
EVs: 252 HP / 36 Def / 220 SDef
Calm Nature
- Shadow Ball
- Recover
- Will-O-Wisp
- Ice Beam
Shadow Ball is STAB, Recover is for Recovery (Suprise!), W.O.W. is for crippling opposing physical attacking switch-ins and Ice Beam is coverage.
Changes
- Jellicent > Ferrothorn
Importable:
Hydreigon (M) @ Choice Specs
Trait: Levitate
EVs: 4 Atk / 252 SAtk / 252 Spd
Hasty Nature (+Spd, -Def)
- Draco Meteor
- Fire Blast
- Dark Pulse
- U-turn
Ninetales (F) @ Leftovers
Trait: Drought
EVs: 108 HP / 4 Def / 144 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- SolarBeam
- Flamethrower
- Sunny Day
- Will-O-Wisp
Cloyster (F) @ Leftovers
Trait: Skill Link
EVs: 248 HP / 84 Atk / 176 Def
Impish Nature (+Def, -SAtk)
- Icicle Spear
- Rapid Spin
- Spikes
- Ice Shard
Venusaur (M) @ Black Sludge
Trait: Chlorophyll
EVs: 252 Atk / 4 SAtk / 252 Spd
Lonely Nature (+Atk, -Def)
- Growth
- Power Whip
- Earthquake
- Hidden Power [Rock]
Xatu (F) @ Leftovers
Trait: Magic Bounce
EVs: 248 HP / 204 Def / 56 Spd
Bold Nature (+Def, -Atk)
- Thunder Wave
- U-turn
- Roost
- Heat Wave
Jellicent (M) @ Leftovers
Trait: Water Absorb
EVs: 252 HP / 36 Def / 220 SDef
Calm Nature (+SDef, -Atk)
- Shadow Ball
- Recover
- Will-O-Wisp
- Ice Beam