FIrst off, a huge thanks to my guy EnderHerve for inspiring me to build around Choice Band Dhelmise. It's a really strong breaker that really only can be checked by Mandibuzz or something like a knocked Buzzwole or Zapdos. I added some faster threats like Keldeo, Weavile, and Volcarona, which all appreciate Dhelmise's ability to force heavy damage on the likes of the birds (Zap, Torn, Corv), physical tanks (Buzzwole, Melmetal, Ferrothorn), or supposed resists (looking at you, Heatran). Garchomp and Melmetal help manage the birds and other weirdos such as Clefable and Slowking-Galar. You may have noticed that there are no Ground immunities or dedicated Kartana checks. This looks pretty bad, but when I was testing this team, it usually came down to winning before the opponent does.
Dhelmise: This guy hits like an orbital strike. Banded Poltergeist 2HKOs pretty much any non-resist, and Power Whip hits just as hard if you can find a neutral target. Earthquake and Anchor Shot are used to hit knocked targets such as Heatran and Buzzwole.
Keldeo: Keldeo is like Urshifu if he didn't have to use Protective Pads. He does things like forcing out Grounds and Steels and emergency checking Weavile. I'm definitely biased towards using this mon, but the speed over Garchomp & Blacephalon and ability to OHKO Ferrothorn with Aura Sphere is really nice. He also brings in Dhelmise on a Flip Turn.
Weavile: Weavile applies fast pressure to targets such as Tornadus and revenges Garchomp. There's some anti-synergy with Weavile clicking Knock Off, but usually this guy isn't the one to apply pressure early on so it ends up working out.
Volcarona: The matchup moth is always waiting in the back for the opponent to give it a chance to work its magic. It dissuades Kartana & Weavile from clicking some of their STABs and can take the game away if checks such as Heatran and Landorus-T are forced to eat a Poltergeist from the GOAT.
Garchomp: Specially defensive Garchomp holds the line versus things such as Blacephalon, Tapu Koko, Volcarona, Heatran, opposing Landorus, Zapdos, etc. It can often trade hazards and Toxic something, which is quite nice for this team.
Melmetal: Melmetal is the dedicated resist to Tapu Lele, which would inhale this team otherwise. It's also a trade machine that can deny things like Garchomp from setting up and generally glues the team together.
Notes
The lack of a great answer to things like Landorus-T, Kartana, and SD Garchomp is probably this team's biggest flaw. This team could probably use a Tornadus or Landorus on it, but I wasn't able to flesh that out and test it. I do like how Dhelmise + Keldeo ended up doing in testing, so I'll see if this build has any further potential.