Using WikiPatches: If you want to allow other wikis to include your pages, you need WikiPatches/RawMode. If you want to include other stuff into your pages, you need WikiPatches/RawWikiInclusion. This makes Transclusion on the page level possible, provided that the TextFormattingRules are similar enough.
AtisWiki supports a form of transclusion by means of transclusion markup: a page consisting of an url preceded by an exclamation mark is placed in an IFRAME. The page must be written in 'transclude' mode.