Tasofro's seriously gotten kinda behind in the "adding characters" department.
Characters from EoSD: in the unpatched version of IaMP, three. As of UNL, five.
Characters from PCB (counting Alice, since every official work uses her PCB character-design): four playable, plus Ran and Chen are in Yukari's spellcards.
(From SWR on begins here)
Characters from IN: one.
Characters from PoFV: two.
Characters from MoF: none (Aya doesn't count, she's from PoFV); two were playable, with Kanako as one of Sanae's attacks.
Characters from SA: one.
.....
You know you're addicted to Touhou based on how much time you spent working that out.