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?
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.
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.