A bit of
Yard Hate. This is pretty important to me because I find that graveyard decks are very prolific in the format. Decks like
Tortured Existence or exhume||Reanimator seem really common, so 3-4 slots should be devoted to dealing with those decks.
A bit of land hate for Tron. This deck reasonably easily stifles the archetype in my experiences, I also don't see it very often, so why devote more than I need to hating the archetype?
Duress is in the sideboard because a lot of decks in pauper are either creature-heavy (i.e. Goblins, GW Slivers) or alternate contral decks (i.e. UB teachings, B LD). This is obviously really unlikely to do much in aggressive deck matchups, but in matchups vs. control, it is far more powerful, taking a removal spell to get down a threat. As Duress is for combo/control matches, there is an additional copy of Cuombajj Witches, which slows aggro decks. It almost guarantees a win if you manage to get 2 down (most aggressive goblins only have 2 toughness).
Lastly, there is some extra miscellaneous removal that could be boarded in under almost any match, but are intended for specific matchups, like Hexproof (i.e. Bogles, Striped Riverwinder reaniator), Tokens (i.e. Midnight Gond, Best Wrath in Pauper for... Well, being the best wrath in pauper. Last of the side removal is Unmake. This is just generally good unconditional removal.
Finally, there's another copy of Death Denied in the sideboard for against other controlmatches, where you can refill your hand with a potentially game-winning combination of miscellaneous Devoters and Gray Merchant of Asphodel.
