[Chou Toshio]

As one of the users quoted in the OP, I'm really thrilled this is happening... The Arceus forme overviews are just awful, so this will definitely be a worthwhile endeavor.

Focus on the useful competitive information. For instance:

Poison Arceus:

Poison may seem an odd choice for Arceus, as Poison is often regarded with incredulity over all competitive metagames for its poor offensive coverage and weakness to the ever-popular Earthquake. Despite the weaknesses generally associated with Poison-typing, Poison Arceus is able to utilize the strengths of Poison to fill a very effective support role and defensive pivot. Poison grants Arceus two important utilities: an immunity to Toxic, and the ability to absorb Toxic Spikes. Toxic Spikes is a sever problem to some of Uber's key threats, such as Groudon, Kyogre, Palkia, and the special walls Blissey and Chansey. Poison Arceus is the best, and perhaps only truly good Poison-type that can be used in Ubers to absorb Toxic Spikes (the only other Pokemon commonly considered being Tentacruel). Furthermore, His immunity to poison allows Him to set up Calm Minds easily against a variety of defensively-oriented opponents, notably Blissey and Chansey, giving Him the ability to translate defensive utility into a significant offensive threat. Poison can't match Dragon or even Normal in terms of coverage, but can be lethal with the setup opportunities granted by Poison's useful resistances and immunity to Toxic. Just like any of Arceus's forms, Poison Arceus is not to be underestimated.

^how's that? of course, if someone who plays ubers regulary can do better, go for it.