Amemura (Arceus) @ Flame Plate  
Ability: Multitype  
Level: 50  
Tera Type: Water  
EVs: 188 HP / 4 Def / 180 SpA / 4 SpD / 132 Spe  
Modest Nature  
IVs: 0 Atk  
- Judgment  
- Heat Wave  
- Thunderbolt  
- Protect  

Slot 3 is more or less a variable coverage move. Picked Thunderbolt as I had several cases of staring down something that went Tera Water, but Earth Power, or more ambitiously Solar Beam or Grass Knot are probably also fine.

Bannings (Groudon) @ Clear Amulet  
Ability: Drought  
Level: 50  
Tera Type: Fire  
EVs: 132 HP / 84 Atk / 4 Def / 172 SpD / 116 Spe  
Adamant Nature  
- Precipice Blades  
- Heat Crash  
- Swords Dance  
- Protect  

EV'd to outspeed max speed Modest Specs Miraidon after an Icy Wind from Flutter Mane. Otherwise it sure is a Clear Amulet Groudon build that will miss Precipice Blades when it matters most.

Teotoratta (Flutter Mane) @ Focus Sash  
Ability: Protosynthesis  
Level: 50  
Tera Type: Stellar  
EVs: 4 Def / 252 SpA / 252 Spe  
Timid Nature  
IVs: 0 Atk  
- Moonblast  
- Shadow Ball  
- Icy Wind  
- Protect  

Genuinely if you see Calyrex Shadow just blast it with Shadow Ball immediately or maybe protect to see if it teras first.

Ecclesia (Ogerpon-Cornerstone) (F) @ Cornerstone Mask  
Ability: Sturdy  
Level: 50  
Tera Type: Rock  
EVs: 252 Atk / 4 Def / 252 Spe  
Jolly Nature  
- Ivy Cudgel  
- Power Whip  
- Taunt  
- Spiky Shield  

You could probably run Grassy Glide over Taunt if you want.

Benjamin (Farigiraf) @ Leftovers  
Ability: Armor Tail  
Level: 50  
Tera Type: Water  
EVs: 228 HP / 196 Def / 84 SpD  
Bold Nature  
IVs: 0 Atk  
- Psychic Noise  
- Imprison  
- Trick Room  
- Protect  

Invariably will either be the matchup lynchpin or will sit around doing nothing. Completely checks the Extreme Speed/Shadow Claw Arceus set and is EV'd to survive Annihilape Final Gambit on 7 HP. Otherwise it is here to click Imprison and stay alive. Tera Water to improve survivability against Calyrex-I.

Frankin (Rillaboom) @ Assault Vest  
Ability: Grassy Surge  
Level: 50  
Tera Type: Fire  
EVs: 132 HP / 116 Atk / 4 Def / 4 SpD / 252 Spe  
Adamant Nature  
- Wood Hammer  
- Grassy Glide  
- U-turn  
- Fake Out  

Last mon added to the team to improve the Kyogre matchup. Fake Out plus a hard hitting attack is probably your most reliable Darkrai out.