Gen 3 Tools' Anti Exploud decapitalizes some stuff, at least. It doesn't seem to decapitalize actual dialogue, though, and I had to use Move Editor to get a couple of moves that G3T missed (which,
this seems to be the thread for the latter tool? I got mine elsewhere, so I'm not sure).
I'd honestly like to know how to decapitalize some text that I'm not sure how to, such as in the Birch intro speech, Wallace's spiel when you fight him/after beating him, and some in battle text.