I use the 1.7dev-318 with API 3.0.0-ALPHA9 Pocketmine.phar, I have downloaded some plugins from here http://forums.pocketmine.net/plugins/, and put them in the plugins folder, but it seems like I cannot use any commands from those plugins, they are not successfully installed.
Most likely the plugins are completely outdated, for more updated plugins get then here: poggit.pmmp.io