As it stands now, the Tainted Dokis' unique starting items are completely exclusive to them, so I've been brainstorming some ideas for how these items could work if used by other characters (as if they were unlocked)

Happy Thoughts - Buffs are halved compared to Tainted Sayori, but no longer grants or removes Curse of Darkness.

Cupcake Platter - (Can't really think of anything different to do here).

Debug - Removes the nearest enemy shot and grants its effect(s) for the current room.

Yuri's Knife - Base charge increased to 3 rooms; using it will deal a full heart of self-damage and grant the effects of Mom's Knife for the current room (basically a knife version of Sulfur), as well as a trail of dark-red creep that deals 44% of the player's damage.