First of all, your EV spreads are...questionable. You should consider just using the spreads that Pokemon Showdown suggests for you for now. Also, you have no Natures on any of your Pokemon.
Calyrex-Shadow: 48 SpA?? You need 252 SpA so you hit as hard as possible. The Shadow Rider is decently bulky so you don't need any real defense investment, plus there's really nothing that you can survive with defense EVs. No amount of defense is gonna help you survive that Yveltal Sucker Punch or Blacephalon Shadow Ball. Here's the spread you should run: 4 Def / 252 SpA / 252 Spe with a Modest nature. I also suggest running Draining Kiss over Dark Pulse for recovery and hitting Dark-types.
Regieleki: This EV spread is, no offense, bad. You have no SpA investment and a small Spe investment. Run this: 80 Def / 252 SpA / 172 Spe. The Def investment is to help tank Earthquakes. Also, run a Timid nature. You also don't need Agility. Regieleki with this spread even outspeeds fully invested Ninjask. True, it boosts Electro Ball, but you'll be doing pretty good damage with Electro Ball against most Pokemon anyway. Use Explosion over Agility and Volt Switch over Extreme Speed, as you don't really need priority when you outspeed everything. Also, why do you have Wide Lens when all your moves are 100% accuracy? Use Magnet instead.
Rayquaza: Make this Mega. You don't have a Mega yet and you need one. Also, a lot about this set is just bad. Don't use Dragon Fang, use Life Orb or Choice Band as it boosts all your moves, not just one, or Choice Scarf for the speed boost.. Don't use a defensive IV spread on Rayquzza. Ever. Don't use 0 Attack IVs, and your moves are subpar compared to the many strong moves Rayquaza has. Use this:
Rayquaza-Mega @ Life Orb / Choice Band / Choice Scarf
Ability: Delta Stream
EVs: 252 Atk / 4 SpD / 252 Spe
Lonely Nature
- Dragon Ascent
- V-Create
- Extreme Speed
- Dragon Dance (or Draco Meteor if Choice Band or Scarf)
Rillaboom: Use 252 Atk EVs, not 252 SpD, and put the remaining 4 in SpD. Run an Adamant nature. Use Life Orb over Terrain Extender, as you don't have anything else that depends on Grassy Terrain, and run the moves Grassy Glide, Knock Off, Swords Dance, and Drain Punch.
Zacian-Crowned: Stop. Running. Defensive. EV. Spreads. Do this:
Zacian Crowned @ Rusted Sword
Ability: Intrepid Sword
EVs: 252 Atk / 4 Def / 252 Spe
IVs: 0 SpA
Adamant Nature
- Behemoth Blade
- Psychic Fangs
- Close Combat
- Play Rough
Kyogre-Primal: Use 4 Def/ 252 SpA / 252 Spe EVs. Run Origin Pulse over Surf, Calm Mind over Earthquake, and Thunder over Thunderbolt.
So here's the improved team:
Calyrex-Shadow @ Ghostium Z
Ability: As One (Spectrier)
EVs: 4 Def / 252 SpA / 252 Spe
IVs: 0 Atk
Modest Nature
- Astral Barrage
- Psychic
- Draining Kiss
- Energy Ball
Regieleki @ Magnet
Ability: Transistor
Shiny: Yes
EVs: 80 Def / 252 SpA / 172 Spe
IVs: 0 Atk
Timid Nature
- Thunder Cage
- Electro Ball
- Explosion
- Volt Switch
Rayquaza-Mega @ Life Orb / Choice Scarf / Choice Band
Ability: Delta Stream
EVs: 252 Atk / 4 SpD / 252 Spe
Lonely Nature
- Dragon Ascent
- V-Create
- Extreme Speed
- Dragon Dance / Draco Meteor
Rillaboom-Gmax @ Life Orb
Ability: Grassy Surge
Gigantamax: Yes
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Swords Dance
- Grassy Glide
- Drain Punch
- Knock Off
Zacian-Crowned @ Rusted Sword
Ability: Intrepid Sword
EVs: 252 Atk / 4 Def / 252 Spe
IVs: 0 SpA
Adamant Nature
- Behemoth Blade
- Close Combat
- Play Rough
- Psychic Fangs
Kyogre-Primal @ Blue Orb
Ability: Primordial Sea
EVs: 252 SpA / 4 SpD / 252 Spe
IVs: 0 Atk
Modest Nature
- Origin Pulse
- Ice Beam
- Calm Mind
- Thunder
