They had part of Marnie Piper's bet if Halloweentown students make it through the Mortal World without the threats of the Knights of the Iron Dagger, and if humans appreciate Halloweentown creatures like they were one of them, Marnie and her family can keep their powers and the portal will stay opened. The leader was Edgar Dalloway. The councilors include, a six armed man, a pumpkin headed man, a mummy and a vampire.
Once Edgar had been revealed to be behind all the supposed knight attacks, they imprisoned him in a witch's glass and stripped him of his magic. They interfered not further afterwards, now content with Marnie's plan having succeeded in reuniting the two worlds.
They apparently haven't researched the mortal world and its history well. Marnie commented that they "needed to get out more often", subtly laughing at the idea that they still think actual knights existed in the 21st century. However, "knighthoods" were still practiced.
The centipede man and the pumpkin-headed man did most of the talking during the meetings; the vampire stayed silent while the mummy could only speak with signs he held up. Dalloway made any final decisions.