[White Council] When the White Council attacked Dol Guldur...

[Man-of-the-Wold]

Although party to the discussions of the Wise, Thranduil would not have been a member of the White Council. He was wise and powerful, but not in that way. He certainly was not in touch with Gandalf or aware of his activities, until he showed up in Dale before the battle.

I generally think that Radagast was a member, if not a key one, and besides the known members (Galadriel, Elrond, Gandalf & Saruman), it is arguable that the Council also included: Cirdan (or designee), Celeborn, Glorfindel and Erastor, making for nine members

How many of these persons were actually present at the Dol Guldor "confrontation" is difficult to say. The impression from the end of The Hobbit is that though he may have been active in the assault, Elrond hadn't actually gone anywhere so far away or seen Gandalf since Thorin & Co. had departed.

Although not primarily a military operation, the White Council's "assault" on Dol Guldor may have involved the marshalling of forces out of Rivendell and in Lothlorien. But probably nothing else.