Slow night, found this list.
No prep, no BFR. Each side knows to fights together; loser's reality is destroyed, so those are the stakes.
DC Comics
the Old Gods
the Skyfathers (Highfather and Darkseid)
the Godly Pantheons of Earth (Greek, Roman, Hindu, Norse, etc)
the Titans
the New Gods (Orion, Metron, etc)
the Alien Gods (Kryptonian and Martian Gods)
the Triarch
the Cancer God
the Hell Lords and Demons
Marvel Comics
the Elder Gods (Gaea, Set, Oshtur and Chthon)
the Great Old Ones (Shuma-Gorath and Hoggoth)
the Elder Spawns (Atum, Agamotto)
the Octessence (Cyttorak, Ikkon, Raggadorr, etc)
the Council of Godheads (Odin, Zeus, Dormammu, Surtur, etc)
the Godly Pantheons of Earth (Norse "Asgardian", Greek, Roman, Egyptian, etc)
the Eternals (Ikarus, Sersi, Makkari, etc)
the Alien Gods (Shi'ar, Skrull, Zen-La, etc)
the Hell-lords and Demons (Mephisto, Satannish, Marduk Kurios, etc)
Better be specific on the Council Of Godheads.I have to point out Surtur and Dormammu are not part of the Council Of Godheads.The reason I said that is because there are 20 plus Pantheons Of Gods in the Marvel Universe.I could understand if its only Zeus,Odin and Vishnu.But If its all the members of the Council Of Godheads, that's 20 plus Skyfather level beings.The Skrull by the way has a Slave Pantheons that consisted of thousands of enslaved Gods by the way.