Proof of Peak:
View attachment 850356
Mega Delphox:
Delphox absolutely demolishes the most common defensive cores of the tier. The combination of Psyshock, Flamethrower/Fire Blast and Dazzling Gleam allow Mega Delphox to 2 hit KO or 1 hit KO practically every single pokemon available with minimal prediction. Even

is quite reliably 2hkod by psyshock. Delphox also has a blazingly fast speed tier, reliably outspeeding Raichu-Y, Non-scarfed Meowscarada, Sneasler, Weavile, Mega Metagross and Mega Starraptor (who are both cleanly 1hKO'd), Garchomp, and even Adamant Blaziken at +1, meaning it can very easily dismantle teams that (very possibly) don't have anything to outspeed it. Nasty plot allows you to turn any 2hko into clean 1-taps, so some Pokemon that may have been able to threaten it before at full health (

) now cannot, allowing Delphox to cut down on the amount of prediction needed to claim kills. Your primary threats as Delphox are

(who is often scarf),

(with scarf or sucker punch),

,

(scarfed or sub),

,

,

,

,

+

, and most of all,
STEALTH ROCKS.
Mega Delphox is easily revenge killed by many common scarfers, but given perfect prediction, Delphox can force a kill every time it comes out. Since you
A: won't have perfect prediction,
B: need a way to switch in to common dark types and water types, and
C: need a way to remove stealth rocks against common setters, the perfect partner for

in COU is:
Hisuian Decidueye:
With a Max/Max Defensive spread, Hisuian Decidueye absolutely hard-counters (most)

sets, who is by far the most common and scariest counter to your

. With a Grass/Fighting typing, you are able to switch into and threaten many of

's counters and slow pivot out into

to force another kill. With access to Roost, Defog and Scrappy, you also happen to be able to deal with the other two non-dark type problems for

, ghost types and stealth rocks. In spite of his PU standing in Generation 9 and his absolutely underwhelming statline, Hisuian Decidueye is somehow a genuinely incredible pick and has been such a high performer even in some of the hardest games I had while laddering. Here are some of the pokemon Decidueye has managed to absolutely 1v1:

(Not A Reliable List Of Things It Can Check)
Hisuian Samurott:
Adamant Black Glasses Hisuian Samurott is so good it might be bannable. Swords Dance boosts your power to unholy levels, and Ceaseless Edge lets you lay down free spikes on top of killing whatever you're trying to kill. I'm not going to spend too much time talking about the Unholy Otter, you all know what it does, but I have grown to enjoy bulky SD as one of its most powerful sets. It is very good as a partner to

, as it has a tendency to solo-win the rain matchup and both softens-up for Delphox and enjoys sweeping teams softened-up by Delphox. Black Glasses Sucker Punch helps pick off or outright kill speedy threats, which is a big boon for the team. 10 Spe invest is to speed-creep anything speed-creeping rotoms.
Dragonite:
Though much less common than in SVOU, Fat DD Dragonite remains an extremely strong "anti-bullshit" pick for Bulky Offense. Espeed Earthquake Roost DD with enough speed to outspeed Pult at +2. Easy Money. Acts as both a defensive piece and a late game sweeper once corv is weakened or killed by

or

. Leftovers lets you heal off some the oft unavoidable Stealth Rock damage without having to waste roosts in long games. If

can't handle the rain matchup alone, Dragonite and Samurott can overwhelm their checks together.
Clefable:
The defensive glue for the team, as well as the mandatory fairy type. Was initially a

in the first draft of the team, but the consistent healing of
soft-boiled Moonlight, access to rocks, and a better matchup into

and

made Clefable a much better pick. Magic Guard Life Orb Clef lets you fire off extremely powerful Moonblasts and Flamethrowers on top of being able to switch in on the ever-present hazards that would make Unaware Clefable cry, making it a very reliable wall against anything that might get too out of control for the previous 4 to handle.

in particular can be tough for the team to handle without Clefable.
Excadrill:
The mandatory Ground type and Steel type. Scarf Drill was the only logical choice once the other 5 were picked, and mold breaker Earthquake is a very scary cleaner against weakened teams. Offers a second form of removal in case

needs to stay healthy or can't get the fog off. Mold Breaker Stealth Rock may also be a life-saver against Hatterene Rain, or if Clefable can't come out until later. Drill helps against

and

, that can all be very very scary to deal with if Delphox is too low.
Try it out!
Paste:
Replays:
Vs
S1nn0hC0nfirm3d:
https://replay.pokemonshowdown.com/gen9championsou-2654289558-sdn295mfsbln2jgqe7p057vkfqmv60fpw
Vs
OatIsHere :
https://replay.pokemonshowdown.com/gen9championsou-2654273430-amhhc7jpvjh25haefouea3x764vikuypw
Vs Stall:
https://replay.pokemonshowdown.com/gen9championsou-2654392704-kgnebfrus7r14pnq7rx2164lg3wxxrnpw
https://replay.pokemonshowdown.com/gen9championsou-2654252044-t0w3yq1nd8c09jpejuriyslrueop8ejpw
https://replay.pokemonshowdown.com/gen9championsou-2654242428-5n9cwtr2jq0hr8cawor1005yltbgp36pw
Vs Rain:
https://replay.pokemonshowdown.com/gen9championsou-2654249693-f4nayevy1vqaae53wxt1d7obgf64k94pw