I believe the Genesis passage is an example of what is called "The Plural of Majesty", a rhetorical device when a monarch speaks in the plural to refer to their own decision or policy or rule or whatever. The Monarch (King) as head of state is a representation and even in some respects a personification of the whole nation/kingdom. So when the King makes a decision it is the decision of the whole Kingdom, as the King essentially embodies the entirety of government in his person.
I don't know that I would call it the "
angelic council", because that implies the angels are advisors to God and offer advice. Perhaps they do, perhaps He deigns to allow them to try out their ideas. But I think the main thing is that when God acts as King He acts on behalf of the whole Kingdom, and His government acts with Him. Same thing as here:
And the LORD came down to see the city and the tower, which the children of men builded. And the LORD said, Behold, the people is one, and they have all one language; and this they begin to do: and now nothing will be restrained from them, which they have imagined to do. Go to, let us go down, and there confound their language, that they may not understand one another's speech.
(Gen 11:5-7)
Now, when God does something, He not only does it on behalf of the whole Kingdom, but often uses angels to get the job done. So the Plural of Majesty is more than just a semantic thing, it is rooted in a reality of the Monarch acting in unison with His Kingdom.
Now, in the Psalm, the Hebrew reads "Elohim stands in the assembly of El." The Greek and Latin read "God stands in the synagogue/assembly of the gods". The assembly or congregation of El ("God") is obviously Israel, the covenanted people of God, the ekklesia or called out assembly of God. He stands in His assembly, and He judges among the "elohim", or "gods". This term elohim was sometimes applied to the rulers and judges of His people. The word literally means "the powers".
How long will ye judge unjustly, and accept the persons of the wicked? Selah. Defend the poor and fatherless: do justice to the afflicted and needy. Deliver the poor and needy: rid them out of the hand of the wicked. They know not, neither will they understand; they walk on in darkness: all the foundations of the earth are out of course. I have said, Ye are gods; and all of you are children of the most High. But ye shall die like men, and fall like one of the princes. Arise, O God, judge the earth: for thou shalt inherit all nations.
(Psa 82:2-8)
Here, the rest of the Psalm demonstrates to whom He is speaking: the rulers and judges of the congregation of God (Israel). He reproves them for being unjust and unrighteous, demands repentance and the rightful execution of justice, and threatens their doom for failing to do so. So the Psalm is speaking of the earthly government of the Kingdom of God, specifically addressed to the earthly "Court" appointed by God to represent His interests in this world.
Psalm 82 is in a sense a poetic Old Testament equivalent to the "Letters to the Seven Churches" in Revelation in which God's representatives in the earth are reproved for not doing their duty.