Arceus - The Original One
Ruler of Isshu
Yeah and maybe he's intersested in all three beasts and not just suicune it gives the others a role too
He's like Cynthia, he studies rare Pokemon and myths, however he's more interested in owning the myths and legends, unlike Cynthia, who just wants to enjoy them.
He's more Cynthia crossed with a Pokemaniac if you will.
So I could see him chasing all three of them, however I think in these games, it will only be Suicune though.