A replay of the whole match with the ability to slow down and switch points of view from yours to the enemy's, and to see their whole team and what they do, too.
This would be a top-tier update if it were real. So many cheaters, even those with expensive skins, could be banned since you could analyze and show why they are cheating.
Replays usually can't show that something an enemy did never made sense and wasn't even fair.
People with good game sense could record and show the evidence.
Also it would be good to analyze your own match to check what you did wrong, correct your tactics and learn to play better.