Grass Knot does 45.04 - 53.46% to +1 Kyogre, which is a sure 3hko, so Kyogre loses. Only CM + 3 Attacks Kyogre has a small chance to get past Grass Arceus, IF SR is off the field and IF Grass Knot gets low damage rolls.
Assuming Grass Arceus switches into Kyogre who Calm Minds on the switch in, Arceus loses. Kyogre can just get in another Calm Mind after you attack it next turn. At +2 Grass Knot does 33.2% - 40.1% ( This is hardly a 3HKO with leftovers ). Next turn Kyogre Rests and Arceus will lose unless you land a critical hit. Sleep Talk can also pick Calm Mind so generally Grass Arceus needs Calm Mind to counter Calm Mind Kyogre.
Sableye is bad, even Tentacruel can possibly 2HKO you with Scald.