Sun teams are more difficult to play this time around thanks to the weather nerf, plus the overwhelming tactics of rain teams, who have an easier time maintaining Politoed.
Anyway, if you're not using Mega Charizard, you're better off using something else in its place. And if you do stick to Charizard, use Charizard Y as a backup sun inducer, even if this means taking Mawile off the team:
-Fire Blast
-Solar Beam
-Focus Blast
-Dragon Pulse/Roost
Nature: Timid/Modest
EVs: 4 Def/252 SAtk/252 Spe
Item: Charizardite Y
Ninetales is, in a word, outclassed by Zard Y as a sun inducer. You need a way to keep it alive:
-Rest
-Sleep Talk
-Flamethrower
-Will-o-Wisp
Nature: Calm
EVs: 248 HP/140 SDef/120 Spe
Item: Heat Rock
Ability: Drought
or
-Substitute
-Pain Split
-Flamethrower
-Will-o-Wisp/Toxic
Nature: Timid
EVs: 248 HP/8 SAtk/252 Spe
Item: Heat Rock
Ability: Drought
Using HP Fire or Earthquake over Sunny Day or Sleep Powder gives Venusaur a way to deal with Steel Pokemon. It doesn't need all that Speed investment; 228 Speed is enough to outspeed all relevant unboosted threats.
Lum Berry > Sitrus Berry on Dragonite. It also needs Extreme Speed as as strong priority move:
-Dragon Dance
-Outrage/Dragon Claw
-Earthquake/Fire Punch
-Extreme Speed
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Lum Berry
Ability: Multiscale
Since I gave the Mega slot to Charizard, drop Mawile for a Rapid Spinner, like Excadrill:
-Earthquake
-Iron Head
-Rapid Spin
-Rock Slide/Stealth Rock
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Leftovers/Air Balloon
Ability: Mold Breaker
or
-Earthquake
-Iron Head
-Rock Slide
-Rapid Spin
Nature: Adamant/Jolly
EVs: 252 Atk/4 Def/252 Spe (Choice Scarf) or 120 HP/136 Atk/252 SDef (Assault Vest; Adamant only)
Item: Choice Scarf/Assault Vest
Ability: Mold Breaker
Chandelure's high Special Attack seems tempting, but Volcarona is better over it, IMO, as even though it shares a 4x Stealth Rock weakness with Charizard, it has the Speed and special bulk to back up its power:
-Quiver Dance
-Fire Blast/Fiery Dance
-Bug Buzz
-Giga Drain
Nature: Modest
EVs: 136 HP/252 SAtk/120 Spe
Item: Life Orb
Ability: Flame Body