So, I have this team here:
Delta Charizard - Noctem ability
Darkrai - SPD maxed out.
Now, we all know that with the debuff given to fairy types, it is almost impossible to kill darkrai.
Not to mention the fact that it’ll always start first, and thanks to Dark Pulse from both d.c. and darkrai it’s almost impossible for the enemy to win.
Also Dream Eater could be used, -15% hp when the pokémon is asleep.
So yeah, how could you kill that duo?
Fighting types such as Lucario or Heracross. Delta Roselia also is great aginst it since it also benefits from Noctem and has a 4x resist against dark.
Vital Spirit Primeape holding Life Orb with Close Combat or Modest Volcarona holding Chesto Berry with a setup Quiver Dance and then Bug Buzz.
noctem only lasts 5 turns. any quiver dancer with a lum/chesto berry/safeguard/taunt can take out darkrai. a focus blast can also easily destroy it. darkrai’s base speed is not THAT great; there are several megas above that, as well as things like jolteon/aerodactyl. Mega Gengar with focus blast can take out both without much trouble.
also, TBH, i could set up my Muk/ delta muk to use minimize a couple times on Delta zard then recover and bulk up; good luck getting dark void to hit that
Absol with Sucker Punch (Life Orb and New Moon boost) can one hit M.D.Charizard (Sucker Punch should do more than 432 Dmg to M.D.Charizard who has a max of 430 HP)
M.Lopunny with High Jump Kick can one hit Darkrai (High Jump Kick should do more than 376 Dmg to Darkrai who has a max of 344 HP)
(all number calculated at lvl 100, because i was to lazy to calculate stats for lvl 120)
Scarf/mega tyranitar or lum hippowdon and excadrill;
Scarf hoopa unbound and orb/sash deoxys attack can both ohko;
Scarf landorus/thundurus incarnate can ohko darkrai turn 1 with discharge/earthquake and a weakened mega charizard turn 2;
Any of the primals and cloud 9 users stop the weather outright (groudon/xerneas found plenty of use in vgc);
Choice band brave bird
These will just be the common checks in a game of 2v2 as well as 6v6, since your post didn’t make clear what the premise is. If you’re talking Anything Goes then mega rayquaza commonly runs lum berry and dragon dance. This team would be annoying and something to be wary of but it’s by no means centralizing.
However, what if I have Sash on Darkrai and I use Dark void?
Or, if I have 4 pokemons, I could have one with Prankster duo with M.D. Charizard, so Noctem ability is activated and Darkrai’s ready to kill.
Vital Spirit Primeape holding Focus Sash with Close Combat.
You can’t put Primeape to sleep at all, so you waste a turn using Dark Void. CC puts you to 1HP. Even if next turn you use Psychic and however get a critical hit, Primeape resists with Focus Sash and kills your Darkrai with U-Turn or whatever other move.