Hey adding in some official sources like the TV Broadcaster Website. It also does look like this should be only one Season from the Air order as it continuously air as one season with no breaks.

Per The guidelines for anime series in the Contribution Bible, The episodes should be in the same season (season 01) because the series had continuous episode numbers on the Official Website and TV Broadcaster Site.

Source:

• https://en.wikipedia.org/wiki/List_of_Zettai_Karen_Children_episodes
• https://www.tv-tokyo.co.jp/anime/zettai_children/ (Broadcaster website with official episode listing.)

For the specials they can be seen below.

• Special 1: A Grand Banquet! Natsuko and Hotaru`s BABEL Report (39.5 The Recap Special)
• Special 2: Zettai Karen Children: Gentei Kaikin!! OVA Chou Sakidori Special!! (OVA that came with the Comic/Manga for Volume 21)
• Special 3: Zettai Karen Children OVA: Changing Love! Take Back a Stolen Future? (OVA that came out in 2010.)