D&G is the "new" golden trait, which boosts the instant damage part of Odyn, and should help a ton with the aoe burst requirements. Boots are nice for this fight, and the helm is the best dps legendary you could have.
You just won't have the buffer bracers or prydaz might offer you, but they're just that : a buffer if you fuck something up, by no means are they mandatory
You may have seen mention of the grontooth trinket too, it's the heirloom trinket you were able to farm in WoD, that deals a shitton of damage against demons (100% of agatha fight is demons, so ... yeah). I don't think you can farm this anymore tho.
Can't think of any more pieces.