Honestly, sandstorm makes it hard to Baton Pass boosts, given that the passers and recipients may not have enough time to survive on the field, due to Sandstorm chipping away at their HP. You could try if you want.
Tyranitar is slow as heck, and is better off using bulky spreads to take advantage of the 1.5x Special Defense boosts it gets in Sandstorm. It can also use Choice Scarf if you really want it to be fast:
-Stone Edge
-Crunch
-Pursuit
-Superpower
Nature: Adamant
EVs: 180 HP/252 Atk/76 Spe
Item: Choice Band
Ability: Sand Stream
or
-Stealth Rock
-Crunch
-Pursuit
-Fire Blast/Superpower/Stone Edge
Nature: Sassy/Careful
EVs: 252 HP/4 Atk/252 SDef
Item: Leftovers
Ability: Sand Stream
or
-Crunch
-Pursuit
-Stone Edge
-Superpower
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Scarf
Ability: Sand Stream
I know that your team is for a local competition, but just in case, remove Double Team from Garchomp, since your opponents might frown down upon the move. Replace it with Fire Fang or Stone Edge. To make it easier for Garchomp to set up SD, you can use Yache Berry or Haban Berry to weaken Ice or Dragon moves, respectively.
Blaziken is an Uber. Given that your team has a hard time with bulky waters, I'd suggest Ferrothorn to help take them on:
-Spikes/Stealth Rock
-Leech Seed
-Power Whip/Protect
-Gyro Ball/Thunder Wave/Protect
Nature: Relaxed
EVs: 252 HP/88 Def/168 SDef
Item: Leftovers/Shed Shell
Given Alakazam's general fraility, you can opt for Focus Sash to help it live a potentially fatal hit, bar multi-hit moves.
Excadrill can't learn Stone Edge. It can learn Rock Slide, but not that move. Why that's the case is beyond me.
Given how strong (and fast) most of your Pokemon are already, Gorebyss seems like overkill on the team, though it can use Shell Smash to help Tyranitar overcome its Speed problems. Most of your Pokemon are physically-oriented, so Skarmory and Gliscor could be potential problems. Starmie can check/counter both quite nicely:
-Hydro Pump/Surf
-Ice Beam
-Thunderbolt
-Rapid Spin/Recover
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Leftovers
Ability: Natural Cure