Tyranitar - I really like Dagon Dance Tyranitar but it has trouble with winning the weather war. Even with the rpesence of Hippowdon, this is a problem. The reason this is a problem is because I am going to replace T-tar for you. I am going to suggest a different Dragon Dancer and one that is capable of demolishing teams after but one Dragon Dance.
Gyarados @ Leftovers
EVs: 252 Atk / 4 Def / 252 Spd
- Dragon Dance
- Ice Fang
Dragon Dance gets you fast enough to outspeed most other threats, and also gets your Attack high enough to punish the poor soul on the other side of the field. This will usually get you a Moxie boost, and that is quite often then end of the game. Waterfall is STAB and Ice Fang and Earthquake provide efficient coverage.
Hippowdon - You already have SR on Bronzong so I suggest you replace SR with Earthquake. Aso, change his EV spread to 252 HP / 252 Def / 4 SDef. This will allow you to effectively tank a mutlitude of physical moves that you might otherwise have trouble taking. Make his Nature Impish, and change Whirlwind for Roar :P
Now I like Garchomp there but is not helping with our ice weakness or your Water weakness. I am going to sugges a pokemon that resists both Water and Ice, and makes the famous Scizor + Rotom-W core. If you haven't already guessed it, this pokemon is Rotom-Wash.
Rotom-W - So you need a scarfer, and Rotom fits the bill. He synergizes well with the team, and as previously stated perfoems exceptionally well with Scizor.
Rotom-W @ Choice Scarf
EVs: 4 HP / 252 SAtk / 252 Spd
- Hydro Pump
- Volt Switch
- Hidden Power [Ice]
Hydro Pump is your main STAB, and Volt Switch is all-around amazing. Hidden Power [Ice] gets great coverage, and Trock is great for crippling walls such as Blissey.
Scizor - I like LO Scizor but more recently I have been using CB Scizor a lot and it does not disappoint.
Scizor @ Choice Band
EVs: 252 HP / 252 Atk / 4 Spd
- Bullet Punch
Bullet Punch is STAB and hits incredibly hard, as well as hitting first. Pursuit is useful for trapping key opponents and Superpower hits other Steel types. U-turn is STAB as well and hits relatively hard while letting you escape and scout at the same time.
Alakzam - You have some problems here, mainly Hyper Beam and Calm Mind. Alakazam is very frail, and you will be killed on the recharge turn for Hyper Beam, also, you do not have the appropiate bulk to run Calm Mind. Alakazam can be just as deadly in the sand as Reuniclus, and is often overlooked and considered outclassed. However, Alakazam can be used with devastating results if played to his strengths. This is the set I used a while back for the sand and I solemnly swear that it will not let you down.
Alakazam @ Life orb
Trait: Magic Gaurd
EVs: 4 HP / 252 SAtk / 252 Spd
- Focus Blast
- Energy Ball
- Shadow Ball
Pretty straight forward I think, mono attacker set. Psychic is STAB and hits pretty hard, Focus Blast and Energy Ball are coverage for Steels and Gastrodon, and Shadow Ball is for hitting Ghost types and other Psychic types.
Bronzong - I like the use of Heatproof here, as almost every Bronzong you ever see has Levitate. If you have trouble with Ground types I strongly recommend changing to Levitate, but if Heatpoof has been working by all means keep it there. The only thing I am going to suggest for the set is that you change Explosion for Gyro Ball, run a speed lowering nature, and give him 0 IV's in speed. Also, change his EVs to 252 HP / 252 SDef / 4 Def.