Sunny Day teams are made for synergy, Rain teams are meant for sweeping and revenge killing.
Sunny Day teams are meant for synergy b/c its pretty much required each teammate supports the others in order to work. This means have a Flash Fire type like Ninetails or Houndoom with Solar Beam. This means have an EQ resist or Immune Pokemon like Jumpluff or Tangrowth, and this means have a Fast sweeper to make proper use of the Sun like Scarf Typhlosion or Life Orb Exeggutor.
B/c of your use Flying/Fire types, pack a Hitmontop... Why? because it packs more uses than Rapid Spin... Intimidate, Close Combat for Chansey which handles your Special Sweepers like Typhlosion, resists Rock, and Bug Attacks and has a strong SpD.
So Synergy =
Ambipom: Fake-out, U-turn, Taunt, Sunny Day
Breaks sash, prevents Spikes, Uses Sunny Day fast, and U-turns out.
Houndoom: Flash Fire- Solar Beam, Fire Blast, Nasty Plot / Sucker Punch, Dark Pulse
*Chosen to be able to switch in on Psychic Attacks, and hit Psychic types like Uxie and Mespirit harder
Hitmontop: Intimidate - Rapid Spin, Close Combat, Foresight, Stone Edge
*Can take Bug, and Rock attacks. Intimidate makes a threat less of a threat, and Close Combat deals with Chansey and walls like Regirock.
Scarf Typhlosion: Eruption, Fire Blast, Focus Blast, Hidden Power Rock
Next you need a Bulky Water Hitter. And one that can benefit from your team, while abusing the Sun. And perhaps set it up as well...
Tangrowth: Sleep Powder, Power Whip, Earthquake, Rock Slide
Draws in Fire Attacks for Houndoom.
Uxie: Stealth Rock, U-turn, Reflect, Sunny Day
Entry Hazard, Screen help, Sunny Day,