Truth be told, it doesn't really look like a strong set. Volt Switch is pitifully weak on something with "so-so" SpA and no STAB. Cobalion already has an onsite set that uses Close Combat / Stone Edge and HP Ice, so I don't think making a set solely based on Choice Scarf will work. Cobalion shouldn't be revenging Volcorona either, we have Terrakion for that, etc.
The team looks good but your Arceus is quite slow though. Things like Lustrous Orb Palkia can hit you for large damage before dying because a +2 Extremespeed does not OHKO Palkia. Shadow Force is also a risky move, I usually use Shadow Claw.
Watchout for Forretress because it sometimes carries Toxic which will cripple Arceus. It can spin on Deoxys-S, Mewtwo, Groudon before dying. You can set up your sweepers as it spins though so use that to your advantage.
Your team doesn't like RestTalk Kyogre with Calm Mind because Palkia might lose to it. The best way is to just hit it hard with Mewtwo and Groudon or catch it on the switch with Palkia.
It's kind of a pun. To nerds, "1337" is pronounced "leet," which is short for "elite." Do a google search for leetspeak. But it worked out well, since various people suggested cutoffs ranging between 1200 and 1400.