Autobiography / Allegory
Like the Wife of Bath's Prologue, the Pardoner's Prologue is an autobiographical narrative in which he discusses his "tricks of the trade" and, in the process, reveals his sins to his audience. The Pardoner's autobiography borrows its confessional aspect from medieval morality plays, in which characters who represented vices like Lust or Greed would confess their sins as a way of showing the audience what their namesakes looked like.
The Pardoner's Tale is part of the manipulation he practices. It's a morality story he preaches when he's trying to convince people to hand over their money in exchange for pardon. Like those medieval morality plays we just mentioned, in the Pardoner's Tale the characters are allegorical, meaning that they represent abstract concepts rather than real characters. The rioters, for example, primarily represent Greed. The Pardoner is very explicit about the lesson his audience is meant to take away from the tale: radix malorum est cupiditas – greed is the root of all evil. Of course, the Pardoner doesn't mind if his audience also learns another lesson: "show me the money."