https://pokepast.es/8388fc762a933c83
Yveltal @ Heavy-Duty Boots
Ability: Dark Aura
EVs: 248 HP / 8 Def / 252 SpD
Careful Nature
- Roost
- Defog
- U-turn
- Knock Off
Necrozma-Dusk-Mane @ Leftovers
Ability: Prism Armor
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Morning Sun
- Stealth Rock
- Thunder Wave
- Sunsteel Strike
Eternatus @ Black Sludge
Ability: Pressure
EVs: 240 HP / 252 SpD / 16 Spe
Timid Nature
- Toxic
- Recover
- Flamethrower
- Dynamax Cannon
These first three are basically the 'big three', so to speak, of gen eight ubers. When I compared my team to the sample teams posted on smogon, literally every single one had this trio and its not hard to see why when you play the tier a few times. The sets are not always the same but the mons are
Yveltal is almost mandatory because it can do nearly everything and prevents you from autolosing to Calyrex. That is the only thing I know about this tier so I put it on the team with what is probably the most anti Calyrex spread of them all. I just went with u turn because I love that move but this thing has a moveslot syndrome that's almost as bad as Hydreigon's
Necrozma is pretty much the same story as Yveltal except it is against Xerneas. I just put twave on it to slow down opposing Yveltals and Eternatus for the sake of Kyogre. It's also the stealth rocker and has a good defensive typing in genreal but Xerneas was the real deal. It renders the reindeer near useless
Finally is Eternatus. I only picked it because one, I needed a Kyogre answer, and two, it has toxic spikes so having an absorber for it is very nice. It's also very fast for a defensive pokemon and can use dynamax cannon to weaken the water spout
Kyogre @ Choice Specs
Ability: Drizzle
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
- Thunder
- Ice Beam
- Water Spout
- Origin Pulse
For this one, I still needed a breaker. What better breaker than the lord of the seas itself. Just a garden variety Kyogre that spams one move and somehow profits from it
Calyrex-Shadow @ Choice Scarf
Ability: As One (Spectrier)
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
- Trick
- Psyshock
- Grass Knot
- Astral Barrage
I still needed a cleaner for the team and scarf Calyrex fit that role perfectly. I didn't want anything fancy and scarfrex seemed to be the most straightforward choice so I chose it. I went with modest because I want the power and I'm not gonna risk a speed tie against opposing scarfrex. That's what Yveltal is for
Groudon @ Leftovers
Ability: Drought
EVs: 240 HP / 252 Atk / 16 Spe
Adamant Nature
- Stone Edge
- Thunder Wave
- Swords Dance
- Precipice Blades
Finally, I wanted a way to reliably get rid of Eternatus. The team doesn't really have a way of doing just that so I put in Groudon. I switch up leftovers for lum berry because toxic from Yveltal is so annoying but the set remains the same. I went with bulky sd set since I don't really want this to outspeed anything. Thunder wave is again, just to help Kyogre because there's really no other move to fit in