Is it possible to do conditional formatting in Numbers for iOS?
iOS Numbers does not support conditional formatting, and it is removed from the document upon import.

According to http://support.apple.com/kb/HT4648 the following changes are made on iOS (my emphasis):


  3D charts are converted to 2D charts. Chart data is retained and
  editable.
  
  Conditional formatting is removed from imported spreadsheets. Cell
  content is retained.
  
  Table Categories are removed. Tables remain organized and category
  names are retained as static text.
  
  Filters are removed.