I am a HUGE dragon tyope lover and I will probably give you a huge lecture.
The Pokemon that needs the most improvement here is probably DRAGONITE. You are not really taking advantage of multiscale here. Also, What is with the EVs? No attack EVs whatsoever when you obviously have all attacking moves? Not trying to sound mean here, but I dont get it. Why would you give it All Defensive EVs when your moves are all attacking? You nature is Admant, but you give it defensive EVs. Fly has zero competitive use whatsoever. The opponent can just switch to a steel type that resists it. Dragon rush has a bad accuracy, so replace it with dragon claw. Extremespeed is good. Ice punch should be replaced with Fire Punch in my opinion as Fortress and Scizor are quite common in the game. Instead of FLY I would suggest Dragon Dance. It gives An Attack and Speed boost and this allows it to OHKO most pokemon that don't resist a Dragon Claw. Also, give it weakness policy. Id suggest
Dragonite@Weakness Policy
Ability: Multiscale
EVs: 252 Atk, 252 Spe, 4 Spd
-Dragon Dance
-Dragon Claw
-Extremespeed
-Fire punch
If you want to be a troller, then try out the extremely trolly dragonite I invented. Its really good.
Dragonite@Lum Berry
Ability: Multiscale
EVs: 128 Def, 128 Spd, 252 HP
-Dragon Tail
-Thunder Wave
-Roost
-Substitute
Use thunder wave first here to paralyze your target, then Use roost if it dealt damage. You can also use substitute after paralyzing. Make sure you use Dragon Tail after multiscale is reusable at it has decreased priority.
Next is Tyrantrum. Why must you give Defensive EVs to every Dragon type on your team?
Tyrantrums attack barely gets a boost and why is there 100 Spd EVs? Give it a focus Sash and let is use Dragon Dance. It will sweep after that.Give it 252 Attack EVs, 248 Speed, and 8 HP. The moveset is good.
Y would you give a Latios Defensive EVs? It gets NO EVS in Special attack and speed. Also, No Bold Nature. Latios should get 252 special attack and speed, a Timid Nature, and 4 EVs in Defense or something.
Instead of Psychic, use Psyshock. It is good for those specially defensive pokemon.
Altarias EVs..Dude, 252 attack, 248 HP, 8 Spd.
Cotton Guard is ok too
All in all I have too say, dont try to balance the stats out. It doesn't work. Focus on where the pokemon is strong.
Thats it! Other than that, your team is pretty good! Just Fix up the EVS and nature.