Vash's assets can be boiled down to what? That's he's really good at shooting? I mean, he's not moronic but he's not the sharpest knife in the drawer either.
The Joker suffers, or benefits, from being a comic book character. You see, how potent comic book character are depends on the writer - they're as powerful and as difficult to defeat as the writer needs them to be. Spider-Man, for example, will get his arse handed to him by the Black Tarantula one issue and then lay out Doctor Doom the next. The Joker has been similarly inconsistent. Often a physical coward, but has been known - across different media - to put up his dukes and hold his own against Batman.
Essentially, what you need to know is this; the DC Universe is occupied by gods - no two ways about it. Batman is Sherlock Holmes meets Bruce Lee meets, I dunno, John Cena. Superman is a couple steps down from being omnipotent. The Flash runs so fast that speed itself slows down, or some other dumb shit. The Green Lantern controls the power of thought. In this universe of over-powered jock cuntbags, The Joker remains a persistently deadly threat. So deadly, in fact, that every other villain short of Lex Luthor pisses in their pants at the sight of him.
I don't care if you've got, I dunno, a giant cross gun that has lots of littler guns hidden inside - you're fucked.
