Not sure how I feel about Arceus-Grass being A-Tier. I believe Arceus-Fight fits the A-Tier description better than Grass does, so would anyone mind elaborating on why it's placed so high? I realize it combats both Kyogre and Groudon well and can serve as a decent check to dragons, but that's all I see it doing. That definitely gives it a purpose, but I feel it needs a LOT of support to do well, and ultimately believe it should be B-Tier.
Looking at the other A-Tier mons I see Arceus-Grass losing to most of them with relative ease. Many of those are also commonly used alongside Kyogre or Groudon. I realize I should be taking teams into consideration, but I just see it being dead weight more than anything else. I'm all for keeping it A-Tier if everyone agrees, but with the release of Genesect and Kyurem-White I just don't see it fulfilling it's niche that it once had.