A little help with teambuilding (Hydreigon vs. Latios).

[NewbInTraining]

Hi! My friend and I are having a competitive battle (OU Singles) soon so I have to build a team. However, 3 of my attackers are physical ones so I need a Special Sweeper on my team. I am torn between Hydreigon and Latios. I know that Hydreigon has greater bulk and fewer counters, but Latios has the higher Special Attack and Speed Stats. Here is the rest of my team (Without the Pokemon in question):

Haxorus@Life Orb
Ability: Mold Breaker
EVs: 4 HP/252 Atk./252 Spd.
Adamant Nature
- Swords Dance
- Outrage
- Superpower
- Earthquake

Breloom@Life Orb
Ability: Technician
EVs: 4 HP/252 Atk./252 Spd.
Adamant Nature
- Swords Dance
- Mach Punch
- Bullet Seed
- Spore

Cloyster@King's Rock
Ability: Skill Link
EVs: 4 HP/252 Atk./252 Spd.
Naive Nature
- Shell Smash
- Icicle Spear
- Rock Blast
- Hydro Pump

Porygon2@Eviolite
Ability: Trace
EVs: 252 HP/32 Def./224 SpDef.
Calm Nature
- Ice Beam
- Thunderbolt
- Toxic
- Recover

Ferrothorn@Leftovers
Ability: Iron Barbs
IVs: 0 Spd.
EVs: 252 HP/48 Def./208 SpDef.
Relaxed Nature
- Spikes
- Stealth Rock
- Power Whip
- Gyro Ball

Please understand that I am 1) New here, 2) Have only a little competitive experience, and 3) Also have little teambuilding experience. I don't want to know how bad my team is (Seeing as how this is in the competitive discussion and not the RMT section), I just what to know whether I should use Hydreigon or Latios on my team. Also, feel free to suggest sets for me to use (I am leaning toward a Mixed Attacker Set for Hydreigon and a Calm Mind and Life Orb Set for Latios). Thanks!

(Also, please don 't hate me if this thread is in the wrong section of the Forums. This is my very first post here!)

 

[ZarZDodge]

Congratulations on joining Smogon!
1) This really should be in the BW rmt section instead.
2) You need to write a small text for each pokemon explaining the moves, it's role on the team etc.