Your team is decent but here are some suggestions.
Arceus normal is fine but try Arceus ghost and switch out one of your other moves (shadow claw is a keeper) and use brick break. The perfect coverage and normal/fighting immunities are nice.
I love deoxys personally (especially shiny) but having deoxys attack and Mewtwo seems a bit redundant. I recommend a kyurem-w with a choice specs/scarf or life orb set. But you have no rapid spinners and kyurem-w has weakness to stealth rocks.
For Lugia I would run ice beam as your only offensive move to 4x hit rayquaza or other dragons (unless you specifically need to use a flying attack). Also I prefer toxic over paralysis but if you need it for the speed reduction keep it. You could also run reflect and be a physical wall.
Zekrom needs to lose either crunch or shadow claw because they cover the same types. I believe he learns earthquake through TM if so then that is probably your best replacement. (And teravolt lets you hit levitate users)
Your Mewtwo looks great though maybe use shadow ball and some other random move instead of ice beam & thunderbolt. Only do so if you desire Mewtwo to have that random move otherwise this Mewtwo is perfect.
And last darkrai. You may want to have a fire/fighting move for better coverage instead of nasty plot but keep the other moves. This could help if you opponent uses a dark type against you as it will be immune to or take half damage from both your offensive moves.
I hope this was helpful. I mainly was helping your coverage and not much else. Also a speed deoxys lead might be a better choice. I also saw little or no synergy in your team but that doesn't matter as much in singles battles as it does in doubles or triples. Also please tell me if I messed up and I will fix it.
And here is a more specific and helpful links
http://www.serebii.net/potw-bw/
http://www.serebii.net/potw-dp/
Also use the coverage checker located under the advanced section of this site.
