NowTV are not allowed to put whatever they please on the system. As for this Nickelodeon would have to get the show on the system. I think? Yeah I don't really know how it works but the first part is right for sure.
@Anonymous User Season 1 of Thundermans is a boxset with 20 episodes available. Season 3 is catchup and has any episodes from the last 30 days, only the last episode is remaining as the other episodes have since left.