>over 10 posts in>most are straight degeneracy>the other two >>42406324 and >>42406690 are incomplete/incorrect answersThe overall strongest Water Type Pokemon is Primal Kyogre, and the strongest Water move is Fishious Rend from Dracovish, assuming it moves first.
>252+ SpA Kyogre-Primal Water Spout (150 BP) vs. 0 HP / 0 SpD Mew in Heavy Rain: 517-609 (151.6 - 178.5%) -- guaranteed OHKO-VS-
>252+ Atk Choice Band Strong Jaw Dracovish Fishious Rend (170 BP) vs. 0 HP / 0 Def Mew: 532-627 (156 - 183.8%) -- guaranteed OHKO>252+ Atk Choice Band Strong Jaw Dracovish Fishious Rend (170 BP) vs. 0 HP / 0 Def Mew in Rain: 798-940 (234 - 275.6%) -- guaranteed OHKO