Proof? In most other games, it is from sources of evil that monsters spring.
Not really. Zelda games 1-6, monsters are typically ordinary beings that are attracted to evil. Same with the TWW games, same with the FS games....TMC had them all sealed in a chest but otherwise seemingly natural...Boss monsters and Bellum's manifestations aside, TP is the only game where monsters (Twilight) are created by the evil. And the monsters in the Shard dungeons don't share any Twilighty aspects like the bosses, and most of them can be found in other places, so I doubt they're related. Even if they were, it's still not the same power as producing a Shadow version of a person like in FSA.