Shadowverse

You're a bit late, before the update, the Sword deck was the strongest, now it's somewhere near the bottom.

Well, at my noob ranks, it still works fine. And there are a lot of opponents using Sword decks.

And does Dungeon get Shadow creatures on player-to-player battles from its own banishers? (No, it doesn't)

Yes, I checked in the attached video - it doesn't. But for Shadows, they took spells that discard your hand. I don't have any Purgatories anyway, so I won't be able to test it.