I am a great fan of the TMNT 2012 series. The Kraang were not only main antagonists but also the overarching antagonist of all versions of TMNT. I don't know about other versions but they were really cool villains in the 2012 series. Comedic, powerful, impactful, etc. Kraang sub-prime was a great character.
I don't know what you mean by The Core.
