The Chakravyūha or Padmavyūha was a special formation (Vyūha), and knowledge of how to penetrate it was limited to only a handful of warriors on the Pandavas' side, namely Abhimanyu, Arjuna, Krishna and Pradyumna.
#Aniruddha - One who is uncontrollable & unstoppable, One who is the Lord of Manas (Mind), Fourth amongst the four fold manifestation (Chatur-Vyuha) of Lord Vishnu (i.e. Vasudeva, Sankarshana, Pradyumna, Aniruddha)