If you need to get the information from another site or your site using JSON API (https://wordpress.org/plugins/json-api/) you can use this plugin.
For slideshow this plugin use Cycle2 (http://jquery.malsup.com/cycle2).
[getapi url="www.mysite.com" limit="5" type="[CYCLE or LIST]"]:
url: url before ?json=get_recent_posts
limit: number element of json result
type: “Cycle” is a slideshow of thumbs or “List” is the list of post titles