Rate and fix my Sunny team

Sunny team (after fix)
Heatran (M) @ Air Balloon
Trait: Flash Fire
EVs: 252 HP / 100 Def / 156 SDef
Calm Nature (+Def, -Atk)
- Stealth Rock
- Roar
- Lava Plume
- Dragon Pulse

Ninetales (M) @ Life Orb
Trait: Drought
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Fire Blast
- SolarBeam
- Hidden Power [Ground]
- Will-O-Wisp

Dragonite (M) @ Leftovers
Trait: Multiscale
EVs: 4 HP / 252 Atk / 252 Spd
Jolly Nature (+Spd, -SAtk)
- Dragon Dance
- Fire Punch
- Outrage
- ExtremeSpeed

Infernape (M) @ Life Orb
Trait: Blaze
EVs: 252 Atk / 4 SAtk / 252 Spd
Naive Nature (+Spd, -SDef)
- Close Combat
- Mach Punch
- Earthquake
- Overheat

Hitmontop (M) @ Leftovers
Trait: Intimidate
EVs: 252 HP / 156 Def / 100 SDef
Careful Nature (+SDef, -SAtk)
- Fake Out
- Rapid Spin
- Close Combat
- Sucker Punch

Venusaur (M) @ Black Sludge
Trait: Chrolophyll
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- SolarBeam
- Sludge Bomb
- Growth
- Hidden Power [Fire]

On Darmanitan, Belly Drum is way too risky. It's safer to use Life Orb or a Choice item on it:
-Flare Blitz
-Rock Slide
-Earthquake/Superpower
-U-turn
Nature: Adamant/Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Band/Choice Scarf/Life Orb
Ability: Sheer Force

Heatran is a better Stealth Rock user than Aerodactyl because of better bulk and typing. Leads are practically non-existent this gen due to Team Preview:
-Stealth Rock
-Fire Blast
-Earth Power
-Hidden Power (Ice/Grass)/Dragon Pulse
Nature: Modest/Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Air Balloon/Life Orb

Typhlosion is outclassed by pretty much any Fire Pokemon, even though Eruption gives it a niche. Still it's not that good. Infernape can sweep more easily than Typhlosion can, due to higher Speed and a better move pool:
-Fire Blast/Overheat
-Close Combat
-U-turn/Grass Knot
-Mach Punch/Stone Edge
Nature: Hasty/Naive
EVs: 252 Atk/4 SAtk/252 Spe
Item: Life Orb

If you're using Rapid Spin on Hitmontop, make it a defensive one, rather than offensive:
-Rapid Spin
-Foresight/Toxic
-Close Combat
-Stone Edge/Sucker Punch/Rest
Nature: Impish
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
Ability: Intimidate

Your team appears to be weak to Water teams outside of Venusaur. Some Pokemon to consider here are more Chlorophyll users, like Shiftry or Sawsbuck, or Dragon Pokemon (who resist Water), such as Dragonite or Latias. I'll let the other people here decide which Pokemon should go on here.

Well thank you about Heatran part but I think I gonna keep Typhlosion cuz he's much better for a late game cleaner and Hitmontop is also good for offensive too (He's my only priority user).
Or maybe I can remove Typhlosion to use Mach Punch on Infernape. Well thanks you very much anyway!

To reflect new changes, Heatran has to use a Calm nature if it wants to be defensive because most of its resists come from the Special end, as well as the EV spread, 248 HP/100 SDef/160 Spe. For your other 3 slots, replace Fire Blast with Lava Plume because since your current Heatran set is more of a supporter/defender. Use a status move, like Toxic or Will-o-Wisp (in case you don't get the burn from Lava Plume) and Protect, to scout for dangerous moves, in the last 2 slots.

Use Will-o-Wisp or Hypnosis in Ninetales' last slot.

For Infernape, Flare Blitz makes it die faster (in conjunction with Close Combat); use Overheat or Fire Blast instead. EQ is also redundant with its Fighting STAB; use U-turn (to hit and scout enemies simultaneously) or Grass Knot (to hit bulky Waters hard). Of course, you have to make it Hasty/Naive to save the power of your Special moves.

Sure, Substitute can protect Venusaur from status, but you can use Sludge Bomb, as an extra STAB, or Sleep Powder, to temporarily disable a threat, over it.