From what I've seen, there's no indicator for it since the status is cured after you switch. The status Pokeballs would be one, I'd imagine, but they don't exist in every game.
It should also be mentioned that a Pokemon with Trace that copies Natural Cure will cure its condition, but a Pokemon that had its ability suppressed with something like Gastro Acid will not be cured. And yet, from what I've seen it just appears the same as switching normally.