Welcome to Smogon. Unfortunately, while I'm not part of the group that picks teams to add to this thread's OP, I think I can confidently say that this team has too many issues to be a sample team.
Every moveset is non-standard to the point of being suboptimal, so I might at least try and help you pick better sets. Mixed Arceus with Focus Blast and Iron Head without a boosting move isn't achieving very much. Focus Blast would be very weak and Iron Head barely hits anything. You would be better off using Swords Dance Extreme Killer Arceus here. Darkrai is already bad enough with a more standard set, but Hypnosis + Nightmare + Dream Eater Darkrai is both unreliable and extremely gimmicky. All the enemy has to do is switch out and at least half of your moveset becomes useless. Dialga is better off as a Stealth Rock user (and even then is quite niche these days) and has no business running two Steel-type moves (or any really). Primal Groudon's moveset is both redundant (Brick Break hits nothing Primal Groudon's STABs already cover) and suboptimal (Earthquake and Flamethrower are not particularly great). If you're going to run a Kyogre with Earthquake, run Liquidation / Earthquake / Ice Beam / Thunder with max investment in Attack and Speed. Finally, the Deoxys-Attack moveset isn't very good at all. Deoxys-Attack's best option these days is a Psycho Boost / Ice Beam / Superpower set with your choice of Dark Pulse or Pursuit, max SpA / Spe EVs, and a nature that lowers one of its defensive stats in favour of Speed.
This team lacks an arceus forme and this really limits the potential the team has and arguably the Arceus slot is the most important attribute to any ubers team, Mega Lucario is not meta representative, consider Ultra Necrozma as a breaker.
Thank you for the submission, as Aurora pointed out already, each moveset / spread selection is nigh unviable in the ubers metagame. I would suggest trying to get more accustomed to the ubers metagame and seek out resources such as the onsite analyses as well as other subforum resources in order to get a better understanding of the metagame.
On a side note, Sample team submissions have now officially closed, with Sword and Shield release being 7 calendar days away, We feel it is an acceptable time to close public submissions and finalise any works that are required to the thread / teams represented, internally. Please do not post any teams as they will not be evaluated.
Pretty solid team IMO. The only recommendation I would consider is LO/CB Ho-Oh over Specs Yveltal for better match up vs opposing balance and stall and helps vs CM Groundceus. Hex Gengar is something to consider too. If you’re worried about hazards you can try to fit Defog on Ho-Oh.
Unfortunate such a great generation is ending, Ubers will never be the same again. I think the Mega Gengar + Specs Yveltal build should strongly be considered. Yveltal is arguably at its peak in usage and prominence, and this type of team shows off just how perfectly it synergizes with Mega Gengar. Some of the movesets and natures can be optimized based on the current meta, but many great players used similar variants such as PurpleGatorade, except he opted to use Scarf Marsh as a heat tech. That being said, it's been real peeps.