Is This a Good Team?

O.K, last time, I was told I needed 6 Pokemon to make a thread.

Well, I have finally an UU team.

Here they are.

1. Tangrowth
Moves: Power Whip, Earthquake, Rock Slide, Synthesis
Relaxed
Chlorophyll
Item: Leftovers
E.Vs: 252 DEF, 252 HP, 4 SP.D

2.Jynx
Moves: Ice Beam, Nasty Plot, Lovely Kiss, Substitute
Timid
Forewarn
Item:Leftovers
E.Vs: 8 HP, 248 SP.A, 252 SPE

3.Toxicroak
Moves: Nasty Plot, Vacuum Wave,Sludge Bomb, Dark Pulse
Modest
Dry Skin
Item: Life Orb
E.Vs: 252 SP.A, 4 SP.D, 252 SPE

4.Houndoom
Moves: Pursuit, Sucker Punch, Crunch, Fire Blast
Hasty
Flash Fire
Item: Life Orb
E.Vs: 100 ATK, 184 SP.A, 224 SPE

5.Altaria
Moves: Dragon Dance, Outrage, Earthquake, Roost
Adamant
Item: Life Orb
E.Vs: 252 ATK, 4 SP.D, 252 SPE

6.Aggron
Moves: Head Smash, Aqua Tail, Low Kick, Ice Punch
Jolly
Item: Choice Band
E.Vs: 252 ATK, 4 DEF, 252 SPE

I will take any suggestions.

I want to stick with UU Pokemon and I would like some sort of strategy, so I will change Pokemon.

Any suggestions on this team?

3 of your pokes are weak to earthquake.
Maybe use Revenge killing Dugtrio instead or aggron.
Your EV spread should be 128 Speed, 252 HP and 252 def on altaria, because after a dragon dance you can outspeed most things anyway.
Also, jynx is poor because of ice typing. Bring in a miltank for a wall/utility with heal bell, milk drink, stealth rock, and body slam.

Toxicroak: Special Toxicroak is good for catching opponents off-guard, but a physical set is better:
-Substitute
-Focus Punch
-Sucker Punch
-Poison Jab/Stone Edge/Ice Punch
Nature: Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Leftovers/Black Sludge
Ability: Dry Skin

Tangrowth: Hidden Power (Ice) or Sleep Powder could be used over Rock Slide.

Houndoom: It's better with this:
-Nasty Plot
-Flamethrower/Fire Blast
-Dark Pulse
-Sucker Punch
Nature: Hasty
EVs: the EVs you listed
Item: Leftovers/Life Orb
Ability: Flash Fire