I'm new to the whole competitive and I'm using this team on showdown. Is it any good? What can I improve upon. It's been working pretty well so far.

Skarmory @ Leftovers
Ability: Sturdy
EVs: 252 HP / 4 Atk / 252 Def
Impish Nature
- Brave Bird
- Roost
- Spikes
- Whirlwind

Alakazam @ Life Orb
Ability: Magic Guard
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature
- Calm Mind
- Psychic
- Shadow Ball
- Taunt

Excadrill @ Air Balloon
Ability: Sand Force
EVs: 252 HP / 252 Atk / 4 Spd
Adamant Nature
- Earthquake
- Rapid Spin
- Swords Dance
- Rock Slide

Tyranitar @ Life Orb
Ability: Sand Stream
EVs: 252 HP / 4 Atk / 252 SDef
Careful Nature
- Crunch
- Pursuit
- Stealth Rock
- Stone Edge

Charizard-Mega-Y @ Charizardite Y
Ability: Drought
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature
- Flamethrower
- Solar Beam
- Dragon Pulse
- Roost

Garchomp @ Choice Scarf
Ability: Sand Veil
EVs: 4 HP / 252 Atk / 252 Spd
Jolly Nature
- Dragon Claw
- Earthquake
- Outrage
- Stone Edge