Any tips for my Gen 8 OU team?

Question

Garchomp (M) @ Leftovers
Ability: Rough Skin
Shiny: Yes
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Dragon Rush
- Earthquake
- Swords Dance
- Giga Impact

Tsareena @ Leftovers
Ability: Queenly Majesty
Shiny: Yes
EVs: 252 HP / 252 Atk / 4 SpA
Brave Nature
- Energy Ball
- Giga Drain
- High Jump Kick
- Power Whip

Victini @ Leftovers
Ability: Victory Star
EVs: 252 HP / 4 Atk / 252 SpA
Mild Nature
- V-create
- Psychic
- Will-O-Wisp
- Dazzling Gleam

Aegislash @ Leftovers
Ability: Stance Change
Shiny: Yes
EVs: 252 HP / 4 Atk / 252 SpD
Sassy Nature
- Iron Head
- Shadow Ball
- King's Shield
- Swords Dance

Tapu Fini @ Leftovers
Ability: Misty Surge
Shiny: Yes
EVs: 252 HP / 252 SpA / 4 SpD
Modest Nature
IVs: 0 Atk
- Hydro Pump
- Moonblast
- Ice Beam
- Iron Defense

Zeraora @ Leftovers
Ability: Volt Absorb
Shiny: Yes
EVs: 252 Atk / 4 SpA / 252 Spe
Hasty Nature
- Plasma Fists
- Close Combat
- Hyper Beam
- Work Up

Anything I need to change would be appreciated!

Comments

Can you add a few lines of explanation about the Pokemon and sets you have chosen, as described in the rules? This would help the rater to give advice which is parallel to your goal and mindset while building the team.
Also most of the Pokémon and movesets you chose are unviable in SS OU, I'd recommend that you take a look of the sample teams (https://www.smogon.com/forums/threads/3672556/) and the Viability Rankings (https://www.smogon.com/forums/threads/3674058/). The good cores thread would also help (https://www.smogon.com/forums/threads/3657595/). The SS OU subforum (https://www.smogon.com/forums/forums/526/) would help you as a whole, too.

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You mostly have sweepers, I would add some different sets and different support mons. For example, Tapu Fini is great with defog and other support.

Tapu Fini @ Leftovers  / Misty Seed
Ability: Misty Surge  
EVs: 216 HP / 56 Def / 40 SpA / 196 Spe  
Calm Nature  
- Defog  
- Haze  
- Moonblast  / Taunt
- Scald