Not a specific format as such but most use at least similar versions of markdown - grab the markdown source of the page and paste it into another engine, it sho

Not a specific format as such but most use at least similar versions of markdown - grab the markdown source of the page and paste it into another engine, it should turn out similar for the most part. If the destination wiki has a wysiwyg editor you might get away with just copying the text as is and pasting it in. All depends on the software though, so no there isn't a specific wiki format that I know of The issue you'll probably come across is things like categories or custom boxes (MediaWiki) moving to another site.