I'm really conflicted on whether or not this is true going by him saying with certainty that "none of the legendary Pokémon are stronger than Arceus". Did he actually have a look at the base stats?
And yes, I know he also says Minobaste has a high Attack stat, but comparing one Pokémon's single stat in-game to its others is easier than taking a random legendary of which we don't know the base stats and exact IV's/EV's and then comparing that to Arceus' stats.
Well, keep in mind Arceus is the only Pokemon with base stats totaling more than 700 and is the supposed creator of the Pokemon world. While life and death are certainly powerful forces, I would say creation is the most powerful in the universe, or else nothing else would exist.
Playing) Fire Emblem: Awakening, Guild Wars 2 Waiting) Pokemon XY