If God called for a meeting of all gods in existence how many do you think would show up and who might some of them be?

all of them would show up

OKAY?  snore

One GOD all forms.  Say it until it penetrates.

Ok. Let us see what happens on meeting day.
There were all forms of God's before God made his appearance.

Thor might show up for the mead.

Yes I might think so.

Just one
The only one

He just might want to make sure. .

There is only One God ......

You have to reason on the context. 

(2 Timothy 3:16) All Scripture is inspired of God and beneficial for teaching, for reproving, for setting things straight, for disciplining in righteousness,

'Us' in Genesis 1:26 doesn't say there is more than one God. It shows God talking to someone else just like 'us' in Is 1:18. Jehovah created Jesus first and then through Jesus, Jehovah created everything else.

(Isaiah 1:18) “Come, now, and let us set matters straight between us,” says Jehovah. “Though your sins are like scarlet, They will be made as white as snow; Though they are as red as crimson cloth, They will become like wool.

(Colossians 1:15, 16) He is the image of the invisible God, the firstborn of all creation; 16 because by means of him all other things were created in the heavens and on the earth, the things visible and the things invisible, whether they are thrones or lordships or governments or authorities. All other things have been created through him and for him.

The Bible says that there are many gods but only one True God the Father. 

Moses was called a god:

(Exodus 4:16) He will speak for you to the people, and he will be your spokesman, and you will serve as God to him.
(Exodus 7:1) Jehovah then said to Moses: “See, I have made you like God to Pharʹaoh, and Aaron your own brother will become your prophet.

Judges in Israel were called gods:
(Psalm 82:6) “I have said, ‘You are gods, All of you are sons of the Most High.

Jesus was called a god:
(John 1:1) In the beginning was the Word, and the Word was with God, and the Word was a god.

There are many gods but only one True God the Father. 
(1 Corinthians 8:5, 6) For even though there are so-called gods, whether in heaven or on earth, just as there are many “gods” and many “lords,” 6 there is actually to us one God, the Father, from whom all things are and we for him; and there is one Lord, Jesus Christ, through whom all things are and we through him.
(John 17:1-3) Jesus spoke these things, and raising his eyes to heaven, he said: “Father, the hour has come. Glorify your son so that your son may glorify you, 2 just as you have given him authority over all flesh, so that he may give everlasting life to all those whom you have given to him. 3 This means everlasting life, their coming to know you, the only true God, and the one whom you sent, Jesus Christ.

What happened to the others?

There has only ever been one God.. There never was any others..

Maybe God would like to have a meeting with the gods to make some kind of agreement so He can change the first commandment and update to something he has in mind more necessary for this day and age.

Then why would there be need for the first commandment?

Because people make non gods.. gods to them...  The best example of this is the fallen angels.. many of the classical pagan gods where actually inspired by the fallen angels and their offspring in ancient times..   But these where and are not gods.. Angels are created beings.. Created by God..

If the meeting is too early in the morning I think Dionysus might not show up.  He was probably out too late again last night.

Some of the gods like Dionysus should show up since there is parallels in their life stories to the story of Jesus of the New Testament.
Kick his ass outa bed!