I skimmed through the teaser and was able to pick out the following characters:
Iron Man
Captain America
Black Widow
Thor
Hawkeye
Hulk
Captain Marvel
Black Panther
Wasp
Ant-Man (Maybe)
Scarlet Witch
Falcon
Dr. Strange
Vision
Ebony Maw
Proxima Midnight
Cull Obsidian
Corvus Glaive
Thanos
All that’s missing is War Machine, Spider-Man, Winter Soldier, Valkyrie, Korg & Meek, and The Guardians.