While the 'metahumans' Wonder Woman and Flash are quite easily identifiable even for people like me, not knowing the comics nor the Arrow and Flash TV series, I would like to know who the other two are?
1 Answer
Those two metahuman/superhero are:
Victor Stone / Cyborg (played by Ray Fisher): A boy whose partial remaining body got attached with mother box to make him cyborg.
On the top right there is partial remaining body of Victore stone and on the right bottom is the Mother Box which is responsible in his creation in comics and in animated film.
Arthur Curry / Aquaman (played by Jason Momoa): The man under the sea.
Copied from my own answer on Movies and TV Stack Exchange for the similar question.