Why would piece of content of each content type be migrated but their text formats wrong?
You need to map the body format. 

This is from 6 years ago, but reposting in case mikeryan does not see this question.


  if the format is part of the source data (i.e., it varies from node
  to node), you can make use of the source_field feature:


$this-&gt;addFieldMapping('body', 'body')
     -&gt;arguments(array('format' =&gt; array('source_field' =&gt; 'body_format'));


Where body_format is the value from the source db I believe.

It has been a loooong time since I have done a 6 to 7 migration. 

This post might also be of use if you are using migrate_d2d.