Can anyone tell me , am i allowed to use free plugins, modules or extensions for wordpress , joomla or magento template to sekk in themeforest ?
I don’t know about Joomla or Magento, so I won’t address those.
But, the question is: Why would you want to? Plugins already have their place in WordPress. Theme developers have no business adding plugins within themes.
Assuming you did add a few plugins to your theme, do you really want the responsibility of maintaining and updating the plugin code?