In either versus with a 2nd controller or Very Easy Single Fight, select Wonder Woman. Chip your opponents health until it is close to depleted, but not too far as if you deal too much damage you won't have a chance to perform the meter-burn necessary for this trophy.
Once down to about 10% or so, you need to press Back-Forward and Square to perform the Lasso of Truth, while spamming R2 so that you perform the meter-burn variant of it which deals more damage. So if your opponent was on the right side, the combo would look like this:
Once you KO your opponent using this move, the trophy will pop.