>>39979145None. Arceus is superior to Silvally and can also be every type.
If we're to discount Arceus, it's still none. There's a Pokemon of every single type with a higher BST than Silvally (570).
If we're to discount legendaries, then the answer is still none. There's a non-legendary Pokemon of every type with a higher BST than Silvally.
If we discount megas but count legendaries, then Silvally is the strongest poison type.
If we discount both megas and legendaries, we get more answers. Silvally would be the strongest poison, fire, grass, electric, ice, bug, ghost, and fairy type. The only things with higher BST than it are the pseudo-legendaries, Slaking, and Wishiwashi.
