I Picked Skarmory cuz it can damage EKiller Arceus and roost himself, i put him Counter for Pdon fire Punch and boosted things like Arceus, Ho - Oh, M-Salamence and Groudon, Rocky Helmet for Damage and Whirlwind can stop sweeps like Geomancy Xerneas (The Thread of the team) and more stuff
Clefable is for Things like Xerneas and T-Wave himself if he is boosted and Skarmory is dead and Unaware to survive their hits, he can wall Arceus and more, but if dont like it, you can put Heal Bell over T-Wave, but t-wave can help vs Dragons and Pokemon faster than Latias
Latias can 2HKO with Psyshock Primal Groudon and Primal Kyogre, the evs spread is to survive their hits (Ice Beam of Kyogre) and (Dragon Claw of Groudon), she can defog and heal his life and she can be helped with Clefable
M-Sableye is here with taunt to stop Deoxys S with Skill Swap on First turn when u have Prankster and Bounce the hazzards, Foul Play to check Offensive Mons and Recover for heal it
Kyogre Primal checks Primal Groudon with Heavy Rain and Rest Sleep Talk to stall the enemy, Scald can Burn and Ice Beam for Latias / Lugia / M-Salamence, he is the win condition of the team
Finally Arceus Water, I put this mon because it can toxic Primal Groudon, Latias, Xerneas, Yveltal and the walls like Lugia, i put this because he can wall Primal Kyogre if it dont have Thunder, i was thinking on Ground Arceus, but Ground is weak to Kyogre, this team is good, i tested it with good results, hope u like it